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Diffstat (limited to 'src/select.c')
| -rw-r--r-- | src/select.c | 4591 |
1 files changed, 4591 insertions, 0 deletions
diff --git a/src/select.c b/src/select.c new file mode 100644 index 0000000..571a778 --- /dev/null +++ b/src/select.c @@ -0,0 +1,4591 @@ +/* +** 2001 September 15 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This file contains C code routines that are called by the parser +** to handle SELECT statements in SQLite. +*/ +#include "sqliteInt.h" + + +/* +** Delete all the content of a Select structure but do not deallocate +** the select structure itself. +*/ +static void clearSelect(sqlite3 *db, Select *p){ + sqlite3ExprListDelete(db, p->pEList); + sqlite3SrcListDelete(db, p->pSrc); + sqlite3ExprDelete(db, p->pWhere); + sqlite3ExprListDelete(db, p->pGroupBy); + sqlite3ExprDelete(db, p->pHaving); + sqlite3ExprListDelete(db, p->pOrderBy); + sqlite3SelectDelete(db, p->pPrior); + sqlite3ExprDelete(db, p->pLimit); + sqlite3ExprDelete(db, p->pOffset); +} + +/* +** Initialize a SelectDest structure. +*/ +void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){ + pDest->eDest = (u8)eDest; + pDest->iParm = iParm; + pDest->affinity = 0; + pDest->iMem = 0; + pDest->nMem = 0; +} + + +/* +** Allocate a new Select structure and return a pointer to that +** structure. +*/ +Select *sqlite3SelectNew( + Parse *pParse, /* Parsing context */ + ExprList *pEList, /* which columns to include in the result */ + SrcList *pSrc, /* the FROM clause -- which tables to scan */ + Expr *pWhere, /* the WHERE clause */ + ExprList *pGroupBy, /* the GROUP BY clause */ + Expr *pHaving, /* the HAVING clause */ + ExprList *pOrderBy, /* the ORDER BY clause */ + int isDistinct, /* true if the DISTINCT keyword is present */ + Expr *pLimit, /* LIMIT value. NULL means not used */ + Expr *pOffset /* OFFSET value. NULL means no offset */ +){ + Select *pNew; + Select standin; + sqlite3 *db = pParse->db; + pNew = sqlite3DbMallocZero(db, sizeof(*pNew) ); + assert( db->mallocFailed || !pOffset || pLimit ); /* OFFSET implies LIMIT */ + if( pNew==0 ){ + assert( db->mallocFailed ); + pNew = &standin; + memset(pNew, 0, sizeof(*pNew)); + } + if( pEList==0 ){ + pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0)); + } + pNew->pEList = pEList; + pNew->pSrc = pSrc; + pNew->pWhere = pWhere; + pNew->pGroupBy = pGroupBy; + pNew->pHaving = pHaving; + pNew->pOrderBy = pOrderBy; + pNew->selFlags = isDistinct ? SF_Distinct : 0; + pNew->op = TK_SELECT; + pNew->pLimit = pLimit; + pNew->pOffset = pOffset; + assert( pOffset==0 || pLimit!=0 ); + pNew->addrOpenEphm[0] = -1; + pNew->addrOpenEphm[1] = -1; + pNew->addrOpenEphm[2] = -1; + if( db->mallocFailed ) { + clearSelect(db, pNew); + if( pNew!=&standin ) sqlite3DbFree(db, pNew); + pNew = 0; + }else{ + assert( pNew->pSrc!=0 || pParse->nErr>0 ); + } + assert( pNew!=&standin ); + return pNew; +} + +/* +** Delete the given Select structure and all of its substructures. +*/ +void sqlite3SelectDelete(sqlite3 *db, Select *p){ + if( p ){ + clearSelect(db, p); + sqlite3DbFree(db, p); + } +} + +/* +** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the +** type of join. Return an integer constant that expresses that type +** in terms of the following bit values: +** +** JT_INNER +** JT_CROSS +** JT_OUTER +** JT_NATURAL +** JT_LEFT +** JT_RIGHT +** +** A full outer join is the combination of JT_LEFT and JT_RIGHT. +** +** If an illegal or unsupported join type is seen, then still return +** a join type, but put an error in the pParse structure. +*/ +int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){ + int jointype = 0; + Token *apAll[3]; + Token *p; + /* 0123456789 123456789 123456789 123 */ + static const char zKeyText[] = "naturaleftouterightfullinnercross"; + static const struct { + u8 i; /* Beginning of keyword text in zKeyText[] */ + u8 nChar; /* Length of the keyword in characters */ + u8 code; /* Join type mask */ + } aKeyword[] = { + /* natural */ { 0, 7, JT_NATURAL }, + /* left */ { 6, 4, JT_LEFT|JT_OUTER }, + /* outer */ { 10, 5, JT_OUTER }, + /* right */ { 14, 5, JT_RIGHT|JT_OUTER }, + /* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER }, + /* inner */ { 23, 5, JT_INNER }, + /* cross */ { 28, 5, JT_INNER|JT_CROSS }, + }; + int i, j; + apAll[0] = pA; + apAll[1] = pB; + apAll[2] = pC; + for(i=0; i<3 && apAll[i]; i++){ + p = apAll[i]; + for(j=0; j<ArraySize(aKeyword); j++){ + if( p->n==aKeyword[j].nChar + && sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){ + jointype |= aKeyword[j].code; + break; + } + } + testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 ); + if( j>=ArraySize(aKeyword) ){ + jointype |= JT_ERROR; + break; + } + } + if( + (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) || + (jointype & JT_ERROR)!=0 + ){ + const char *zSp = " "; + assert( pB!=0 ); + if( pC==0 ){ zSp++; } + sqlite3ErrorMsg(pParse, "unknown or unsupported join type: " + "%T %T%s%T", pA, pB, zSp, pC); + jointype = JT_INNER; + }else if( (jointype & JT_OUTER)!=0 + && (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){ + sqlite3ErrorMsg(pParse, + "RIGHT and FULL OUTER JOINs are not currently supported"); + jointype = JT_INNER; + } + return jointype; +} + +/* +** Return the index of a column in a table. Return -1 if the column +** is not contained in the table. +*/ +static int columnIndex(Table *pTab, const char *zCol){ + int i; + for(i=0; i<pTab->nCol; i++){ + if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i; + } + return -1; +} + +/* +** Search the first N tables in pSrc, from left to right, looking for a +** table that has a column named zCol. +** +** When found, set *piTab and *piCol to the table index and column index +** of the matching column and return TRUE. +** +** If not found, return FALSE. +*/ +static int tableAndColumnIndex( + SrcList *pSrc, /* Array of tables to search */ + int N, /* Number of tables in pSrc->a[] to search */ + const char *zCol, /* Name of the column we are looking for */ + int *piTab, /* Write index of pSrc->a[] here */ + int *piCol /* Write index of pSrc->a[*piTab].pTab->aCol[] here */ +){ + int i; /* For looping over tables in pSrc */ + int iCol; /* Index of column matching zCol */ + + assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */ + for(i=0; i<N; i++){ + iCol = columnIndex(pSrc->a[i].pTab, zCol); + if( iCol>=0 ){ + if( piTab ){ + *piTab = i; + *piCol = iCol; + } + return 1; + } + } + return 0; +} + +/* +** This function is used to add terms implied by JOIN syntax to the +** WHERE clause expression of a SELECT statement. The new term, which +** is ANDed with the existing WHERE clause, is of the form: +** +** (tab1.col1 = tab2.col2) +** +** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the +** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is +** column iColRight of tab2. +*/ +static void addWhereTerm( + Parse *pParse, /* Parsing context */ + SrcList *pSrc, /* List of tables in FROM clause */ + int iLeft, /* Index of first table to join in pSrc */ + int iColLeft, /* Index of column in first table */ + int iRight, /* Index of second table in pSrc */ + int iColRight, /* Index of column in second table */ + int isOuterJoin, /* True if this is an OUTER join */ + Expr **ppWhere /* IN/OUT: The WHERE clause to add to */ +){ + sqlite3 *db = pParse->db; + Expr *pE1; + Expr *pE2; + Expr *pEq; + + assert( iLeft<iRight ); + assert( pSrc->nSrc>iRight ); + assert( pSrc->a[iLeft].pTab ); + assert( pSrc->a[iRight].pTab ); + + pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft); + pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight); + + pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2, 0); + if( pEq && isOuterJoin ){ + ExprSetProperty(pEq, EP_FromJoin); + assert( !ExprHasAnyProperty(pEq, EP_TokenOnly|EP_Reduced) ); + ExprSetIrreducible(pEq); + pEq->iRightJoinTable = (i16)pE2->iTable; + } + *ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq); +} + +/* +** Set the EP_FromJoin property on all terms of the given expression. +** And set the Expr.iRightJoinTable to iTable for every term in the +** expression. +** +** The EP_FromJoin property is used on terms of an expression to tell +** the LEFT OUTER JOIN processing logic that this term is part of the +** join restriction specified in the ON or USING clause and not a part +** of the more general WHERE clause. These terms are moved over to the +** WHERE clause during join processing but we need to remember that they +** originated in the ON or USING clause. +** +** The Expr.iRightJoinTable tells the WHERE clause processing that the +** expression depends on table iRightJoinTable even if that table is not +** explicitly mentioned in the expression. That information is needed +** for cases like this: +** +** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5 +** +** The where clause needs to defer the handling of the t1.x=5 +** term until after the t2 loop of the join. In that way, a +** NULL t2 row will be inserted whenever t1.x!=5. If we do not +** defer the handling of t1.x=5, it will be processed immediately +** after the t1 loop and rows with t1.x!=5 will never appear in +** the output, which is incorrect. +*/ +static void setJoinExpr(Expr *p, int iTable){ + while( p ){ + ExprSetProperty(p, EP_FromJoin); + assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) ); + ExprSetIrreducible(p); + p->iRightJoinTable = (i16)iTable; + setJoinExpr(p->pLeft, iTable); + p = p->pRight; + } +} + +/* +** This routine processes the join information for a SELECT statement. +** ON and USING clauses are converted into extra terms of the WHERE clause. +** NATURAL joins also create extra WHERE clause terms. +** +** The terms of a FROM clause are contained in the Select.pSrc structure. +** The left most table is the first entry in Select.pSrc. The right-most +** table is the last entry. The join operator is held in the entry to +** the left. Thus entry 0 contains the join operator for the join between +** entries 0 and 1. Any ON or USING clauses associated with the join are +** also attached to the left entry. +** +** This routine returns the number of errors encountered. +*/ +static int sqliteProcessJoin(Parse *pParse, Select *p){ + SrcList *pSrc; /* All tables in the FROM clause */ + int i, j; /* Loop counters */ + struct SrcList_item *pLeft; /* Left table being joined */ + struct SrcList_item *pRight; /* Right table being joined */ + + pSrc = p->pSrc; + pLeft = &pSrc->a[0]; + pRight = &pLeft[1]; + for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){ + Table *pLeftTab = pLeft->pTab; + Table *pRightTab = pRight->pTab; + int isOuter; + + if( NEVER(pLeftTab==0 || pRightTab==0) ) continue; + isOuter = (pRight->jointype & JT_OUTER)!=0; + + /* When the NATURAL keyword is present, add WHERE clause terms for + ** every column that the two tables have in common. + */ + if( pRight->jointype & JT_NATURAL ){ + if( pRight->pOn || pRight->pUsing ){ + sqlite3ErrorMsg(pParse, "a NATURAL join may not have " + "an ON or USING clause", 0); + return 1; + } + for(j=0; j<pRightTab->nCol; j++){ + char *zName; /* Name of column in the right table */ + int iLeft; /* Matching left table */ + int iLeftCol; /* Matching column in the left table */ + + zName = pRightTab->aCol[j].zName; + if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){ + addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j, + isOuter, &p->pWhere); + } + } + } + + /* Disallow both ON and USING clauses in the same join + */ + if( pRight->pOn && pRight->pUsing ){ + sqlite3ErrorMsg(pParse, "cannot have both ON and USING " + "clauses in the same join"); + return 1; + } + + /* Add the ON clause to the end of the WHERE clause, connected by + ** an AND operator. + */ + if( pRight->pOn ){ + if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor); + p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn); + pRight->pOn = 0; + } + + /* Create extra terms on the WHERE clause for each column named + ** in the USING clause. Example: If the two tables to be joined are + ** A and B and the USING clause names X, Y, and Z, then add this + ** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z + ** Report an error if any column mentioned in the USING clause is + ** not contained in both tables to be joined. + */ + if( pRight->pUsing ){ + IdList *pList = pRight->pUsing; + for(j=0; j<pList->nId; j++){ + char *zName; /* Name of the term in the USING clause */ + int iLeft; /* Table on the left with matching column name */ + int iLeftCol; /* Column number of matching column on the left */ + int iRightCol; /* Column number of matching column on the right */ + + zName = pList->a[j].zName; + iRightCol = columnIndex(pRightTab, zName); + if( iRightCol<0 + || !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) + ){ + sqlite3ErrorMsg(pParse, "cannot join using column %s - column " + "not present in both tables", zName); + return 1; + } + addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol, + isOuter, &p->pWhere); + } + } + } + return 0; +} + +/* +** Insert code into "v" that will push the record on the top of the +** stack into the sorter. +*/ +static void pushOntoSorter( + Parse *pParse, /* Parser context */ + ExprList *pOrderBy, /* The ORDER BY clause */ + Select *pSelect, /* The whole SELECT statement */ + int regData /* Register holding data to be sorted */ +){ + Vdbe *v = pParse->pVdbe; + int nExpr = pOrderBy->nExpr; + int regBase = sqlite3GetTempRange(pParse, nExpr+2); + int regRecord = sqlite3GetTempReg(pParse); + int op; + sqlite3ExprCacheClear(pParse); + sqlite3ExprCodeExprList(pParse, pOrderBy, regBase, 0); + sqlite3VdbeAddOp2(v, OP_Sequence, pOrderBy->iECursor, regBase+nExpr); + sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+1, 1); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nExpr + 2, regRecord); + if( pSelect->selFlags & SF_UseSorter ){ + op = OP_SorterInsert; + }else{ + op = OP_IdxInsert; + } + sqlite3VdbeAddOp2(v, op, pOrderBy->iECursor, regRecord); + sqlite3ReleaseTempReg(pParse, regRecord); + sqlite3ReleaseTempRange(pParse, regBase, nExpr+2); + if( pSelect->iLimit ){ + int addr1, addr2; + int iLimit; + if( pSelect->iOffset ){ + iLimit = pSelect->iOffset+1; + }else{ + iLimit = pSelect->iLimit; + } + addr1 = sqlite3VdbeAddOp1(v, OP_IfZero, iLimit); + sqlite3VdbeAddOp2(v, OP_AddImm, iLimit, -1); + addr2 = sqlite3VdbeAddOp0(v, OP_Goto); + sqlite3VdbeJumpHere(v, addr1); + sqlite3VdbeAddOp1(v, OP_Last, pOrderBy->iECursor); + sqlite3VdbeAddOp1(v, OP_Delete, pOrderBy->iECursor); + sqlite3VdbeJumpHere(v, addr2); + } +} + +/* +** Add code to implement the OFFSET +*/ +static void codeOffset( + Vdbe *v, /* Generate code into this VM */ + Select *p, /* The SELECT statement being coded */ + int iContinue /* Jump here to skip the current record */ +){ + if( p->iOffset && iContinue!=0 ){ + int addr; + sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1); + addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset); + sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue); + VdbeComment((v, "skip OFFSET records")); + sqlite3VdbeJumpHere(v, addr); + } +} + +/* +** Add code that will check to make sure the N registers starting at iMem +** form a distinct entry. iTab is a sorting index that holds previously +** seen combinations of the N values. A new entry is made in iTab +** if the current N values are new. +** +** A jump to addrRepeat is made and the N+1 values are popped from the +** stack if the top N elements are not distinct. +*/ +static void codeDistinct( + Parse *pParse, /* Parsing and code generating context */ + int iTab, /* A sorting index used to test for distinctness */ + int addrRepeat, /* Jump to here if not distinct */ + int N, /* Number of elements */ + int iMem /* First element */ +){ + Vdbe *v; + int r1; + + v = pParse->pVdbe; + r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); + sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1); + sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1); + sqlite3ReleaseTempReg(pParse, r1); +} + +#ifndef SQLITE_OMIT_SUBQUERY +/* +** Generate an error message when a SELECT is used within a subexpression +** (example: "a IN (SELECT * FROM table)") but it has more than 1 result +** column. We do this in a subroutine because the error used to occur +** in multiple places. (The error only occurs in one place now, but we +** retain the subroutine to minimize code disruption.) +*/ +static int checkForMultiColumnSelectError( + Parse *pParse, /* Parse context. */ + SelectDest *pDest, /* Destination of SELECT results */ + int nExpr /* Number of result columns returned by SELECT */ +){ + int eDest = pDest->eDest; + if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){ + sqlite3ErrorMsg(pParse, "only a single result allowed for " + "a SELECT that is part of an expression"); + return 1; + }else{ + return 0; + } +} +#endif + +/* +** This routine generates the code for the inside of the inner loop +** of a SELECT. +** +** If srcTab and nColumn are both zero, then the pEList expressions +** are evaluated in order to get the data for this row. If nColumn>0 +** then data is pulled from srcTab and pEList is used only to get the +** datatypes for each column. +*/ +static void selectInnerLoop( + Parse *pParse, /* The parser context */ + Select *p, /* The complete select statement being coded */ + ExprList *pEList, /* List of values being extracted */ + int srcTab, /* Pull data from this table */ + int nColumn, /* Number of columns in the source table */ + ExprList *pOrderBy, /* If not NULL, sort results using this key */ + int distinct, /* If >=0, make sure results are distinct */ + SelectDest *pDest, /* How to dispose of the results */ + int iContinue, /* Jump here to continue with next row */ + int iBreak /* Jump here to break out of the inner loop */ +){ + Vdbe *v = pParse->pVdbe; + int i; + int hasDistinct; /* True if the DISTINCT keyword is present */ + int regResult; /* Start of memory holding result set */ + int eDest = pDest->eDest; /* How to dispose of results */ + int iParm = pDest->iParm; /* First argument to disposal method */ + int nResultCol; /* Number of result columns */ + + assert( v ); + if( NEVER(v==0) ) return; + assert( pEList!=0 ); + hasDistinct = distinct>=0; + if( pOrderBy==0 && !hasDistinct ){ + codeOffset(v, p, iContinue); + } + + /* Pull the requested columns. + */ + if( nColumn>0 ){ + nResultCol = nColumn; + }else{ + nResultCol = pEList->nExpr; + } + if( pDest->iMem==0 ){ + pDest->iMem = pParse->nMem+1; + pDest->nMem = nResultCol; + pParse->nMem += nResultCol; + }else{ + assert( pDest->nMem==nResultCol ); + } + regResult = pDest->iMem; + if( nColumn>0 ){ + for(i=0; i<nColumn; i++){ + sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i); + } + }else if( eDest!=SRT_Exists ){ + /* If the destination is an EXISTS(...) expression, the actual + ** values returned by the SELECT are not required. + */ + sqlite3ExprCacheClear(pParse); + sqlite3ExprCodeExprList(pParse, pEList, regResult, eDest==SRT_Output); + } + nColumn = nResultCol; + + /* If the DISTINCT keyword was present on the SELECT statement + ** and this row has been seen before, then do not make this row + ** part of the result. + */ + if( hasDistinct ){ + assert( pEList!=0 ); + assert( pEList->nExpr==nColumn ); + codeDistinct(pParse, distinct, iContinue, nColumn, regResult); + if( pOrderBy==0 ){ + codeOffset(v, p, iContinue); + } + } + + switch( eDest ){ + /* In this mode, write each query result to the key of the temporary + ** table iParm. + */ +#ifndef SQLITE_OMIT_COMPOUND_SELECT + case SRT_Union: { + int r1; + r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1); + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); + sqlite3ReleaseTempReg(pParse, r1); + break; + } + + /* Construct a record from the query result, but instead of + ** saving that record, use it as a key to delete elements from + ** the temporary table iParm. + */ + case SRT_Except: { + sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nColumn); + break; + } +#endif + + /* Store the result as data using a unique key. + */ + case SRT_Table: + case SRT_EphemTab: { + int r1 = sqlite3GetTempReg(pParse); + testcase( eDest==SRT_Table ); + testcase( eDest==SRT_EphemTab ); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1); + if( pOrderBy ){ + pushOntoSorter(pParse, pOrderBy, p, r1); + }else{ + int r2 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2); + sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2); + sqlite3VdbeChangeP5(v, OPFLAG_APPEND); + sqlite3ReleaseTempReg(pParse, r2); + } + sqlite3ReleaseTempReg(pParse, r1); + break; + } + +#ifndef SQLITE_OMIT_SUBQUERY + /* If we are creating a set for an "expr IN (SELECT ...)" construct, + ** then there should be a single item on the stack. Write this + ** item into the set table with bogus data. + */ + case SRT_Set: { + assert( nColumn==1 ); + p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity); + if( pOrderBy ){ + /* At first glance you would think we could optimize out the + ** ORDER BY in this case since the order of entries in the set + ** does not matter. But there might be a LIMIT clause, in which + ** case the order does matter */ + pushOntoSorter(pParse, pOrderBy, p, regResult); + }else{ + int r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1); + sqlite3ExprCacheAffinityChange(pParse, regResult, 1); + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); + sqlite3ReleaseTempReg(pParse, r1); + } + break; + } + + /* If any row exist in the result set, record that fact and abort. + */ + case SRT_Exists: { + sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm); + /* The LIMIT clause will terminate the loop for us */ + break; + } + + /* If this is a scalar select that is part of an expression, then + ** store the results in the appropriate memory cell and break out + ** of the scan loop. + */ + case SRT_Mem: { + assert( nColumn==1 ); + if( pOrderBy ){ + pushOntoSorter(pParse, pOrderBy, p, regResult); + }else{ + sqlite3ExprCodeMove(pParse, regResult, iParm, 1); + /* The LIMIT clause will jump out of the loop for us */ + } + break; + } +#endif /* #ifndef SQLITE_OMIT_SUBQUERY */ + + /* Send the data to the callback function or to a subroutine. In the + ** case of a subroutine, the subroutine itself is responsible for + ** popping the data from the stack. + */ + case SRT_Coroutine: + case SRT_Output: { + testcase( eDest==SRT_Coroutine ); + testcase( eDest==SRT_Output ); + if( pOrderBy ){ + int r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1); + pushOntoSorter(pParse, pOrderBy, p, r1); + sqlite3ReleaseTempReg(pParse, r1); + }else if( eDest==SRT_Coroutine ){ + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); + }else{ + sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn); + sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn); + } + break; + } + +#if !defined(SQLITE_OMIT_TRIGGER) + /* Discard the results. This is used for SELECT statements inside + ** the body of a TRIGGER. The purpose of such selects is to call + ** user-defined functions that have side effects. We do not care + ** about the actual results of the select. + */ + default: { + assert( eDest==SRT_Discard ); + break; + } +#endif + } + + /* Jump to the end of the loop if the LIMIT is reached. Except, if + ** there is a sorter, in which case the sorter has already limited + ** the output for us. + */ + if( pOrderBy==0 && p->iLimit ){ + sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1); + } +} + +/* +** Given an expression list, generate a KeyInfo structure that records +** the collating sequence for each expression in that expression list. +** +** If the ExprList is an ORDER BY or GROUP BY clause then the resulting +** KeyInfo structure is appropriate for initializing a virtual index to +** implement that clause. If the ExprList is the result set of a SELECT +** then the KeyInfo structure is appropriate for initializing a virtual +** index to implement a DISTINCT test. +** +** Space to hold the KeyInfo structure is obtain from malloc. The calling +** function is responsible for seeing that this structure is eventually +** freed. Add the KeyInfo structure to the P4 field of an opcode using +** P4_KEYINFO_HANDOFF is the usual way of dealing with this. +*/ +static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){ + sqlite3 *db = pParse->db; + int nExpr; + KeyInfo *pInfo; + struct ExprList_item *pItem; + int i; + + nExpr = pList->nExpr; + pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) ); + if( pInfo ){ + pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr]; + pInfo->nField = (u16)nExpr; + pInfo->enc = ENC(db); + pInfo->db = db; + for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){ + CollSeq *pColl; + pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr); + if( !pColl ){ + pColl = db->pDfltColl; + } + pInfo->aColl[i] = pColl; + pInfo->aSortOrder[i] = pItem->sortOrder; + } + } + return pInfo; +} + +#ifndef SQLITE_OMIT_COMPOUND_SELECT +/* +** Name of the connection operator, used for error messages. +*/ +static const char *selectOpName(int id){ + char *z; + switch( id ){ + case TK_ALL: z = "UNION ALL"; break; + case TK_INTERSECT: z = "INTERSECT"; break; + case TK_EXCEPT: z = "EXCEPT"; break; + default: z = "UNION"; break; + } + return z; +} +#endif /* SQLITE_OMIT_COMPOUND_SELECT */ + +#ifndef SQLITE_OMIT_EXPLAIN +/* +** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function +** is a no-op. Otherwise, it adds a single row of output to the EQP result, +** where the caption is of the form: +** +** "USE TEMP B-TREE FOR xxx" +** +** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which +** is determined by the zUsage argument. +*/ +static void explainTempTable(Parse *pParse, const char *zUsage){ + if( pParse->explain==2 ){ + Vdbe *v = pParse->pVdbe; + char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage); + sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); + } +} + +/* +** Assign expression b to lvalue a. A second, no-op, version of this macro +** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code +** in sqlite3Select() to assign values to structure member variables that +** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the +** code with #ifndef directives. +*/ +# define explainSetInteger(a, b) a = b + +#else +/* No-op versions of the explainXXX() functions and macros. */ +# define explainTempTable(y,z) +# define explainSetInteger(y,z) +#endif + +#if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT) +/* +** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function +** is a no-op. Otherwise, it adds a single row of output to the EQP result, +** where the caption is of one of the two forms: +** +** "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)" +** "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)" +** +** where iSub1 and iSub2 are the integers passed as the corresponding +** function parameters, and op is the text representation of the parameter +** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT, +** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is +** false, or the second form if it is true. +*/ +static void explainComposite( + Parse *pParse, /* Parse context */ + int op, /* One of TK_UNION, TK_EXCEPT etc. */ + int iSub1, /* Subquery id 1 */ + int iSub2, /* Subquery id 2 */ + int bUseTmp /* True if a temp table was used */ +){ + assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL ); + if( pParse->explain==2 ){ + Vdbe *v = pParse->pVdbe; + char *zMsg = sqlite3MPrintf( + pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2, + bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op) + ); + sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); + } +} +#else +/* No-op versions of the explainXXX() functions and macros. */ +# define explainComposite(v,w,x,y,z) +#endif + +/* +** If the inner loop was generated using a non-null pOrderBy argument, +** then the results were placed in a sorter. After the loop is terminated +** we need to run the sorter and output the results. The following +** routine generates the code needed to do that. +*/ +static void generateSortTail( + Parse *pParse, /* Parsing context */ + Select *p, /* The SELECT statement */ + Vdbe *v, /* Generate code into this VDBE */ + int nColumn, /* Number of columns of data */ + SelectDest *pDest /* Write the sorted results here */ +){ + int addrBreak = sqlite3VdbeMakeLabel(v); /* Jump here to exit loop */ + int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */ + int addr; + int iTab; + int pseudoTab = 0; + ExprList *pOrderBy = p->pOrderBy; + + int eDest = pDest->eDest; + int iParm = pDest->iParm; + + int regRow; + int regRowid; + + iTab = pOrderBy->iECursor; + regRow = sqlite3GetTempReg(pParse); + if( eDest==SRT_Output || eDest==SRT_Coroutine ){ + pseudoTab = pParse->nTab++; + sqlite3VdbeAddOp3(v, OP_OpenPseudo, pseudoTab, regRow, nColumn); + regRowid = 0; + }else{ + regRowid = sqlite3GetTempReg(pParse); + } + if( p->selFlags & SF_UseSorter ){ + int regSortOut = ++pParse->nMem; + int ptab2 = pParse->nTab++; + sqlite3VdbeAddOp3(v, OP_OpenPseudo, ptab2, regSortOut, pOrderBy->nExpr+2); + addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak); + codeOffset(v, p, addrContinue); + sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut); + sqlite3VdbeAddOp3(v, OP_Column, ptab2, pOrderBy->nExpr+1, regRow); + sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE); + }else{ + addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); + codeOffset(v, p, addrContinue); + sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr+1, regRow); + } + switch( eDest ){ + case SRT_Table: + case SRT_EphemTab: { + testcase( eDest==SRT_Table ); + testcase( eDest==SRT_EphemTab ); + sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid); + sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid); + sqlite3VdbeChangeP5(v, OPFLAG_APPEND); + break; + } +#ifndef SQLITE_OMIT_SUBQUERY + case SRT_Set: { + assert( nColumn==1 ); + sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, &p->affinity, 1); + sqlite3ExprCacheAffinityChange(pParse, regRow, 1); + sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid); + break; + } + case SRT_Mem: { + assert( nColumn==1 ); + sqlite3ExprCodeMove(pParse, regRow, iParm, 1); + /* The LIMIT clause will terminate the loop for us */ + break; + } +#endif + default: { + int i; + assert( eDest==SRT_Output || eDest==SRT_Coroutine ); + testcase( eDest==SRT_Output ); + testcase( eDest==SRT_Coroutine ); + for(i=0; i<nColumn; i++){ + assert( regRow!=pDest->iMem+i ); + sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i); + if( i==0 ){ + sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE); + } + } + if( eDest==SRT_Output ){ + sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn); + sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn); + }else{ + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); + } + break; + } + } + sqlite3ReleaseTempReg(pParse, regRow); + sqlite3ReleaseTempReg(pParse, regRowid); + + /* The bottom of the loop + */ + sqlite3VdbeResolveLabel(v, addrContinue); + if( p->selFlags & SF_UseSorter ){ + sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); + }else{ + sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); + } + sqlite3VdbeResolveLabel(v, addrBreak); + if( eDest==SRT_Output || eDest==SRT_Coroutine ){ + sqlite3VdbeAddOp2(v, OP_Close, pseudoTab, 0); + } +} + +/* +** Return a pointer to a string containing the 'declaration type' of the +** expression pExpr. The string may be treated as static by the caller. +** +** The declaration type is the exact datatype definition extracted from the +** original CREATE TABLE statement if the expression is a column. The +** declaration type for a ROWID field is INTEGER. Exactly when an expression +** is considered a column can be complex in the presence of subqueries. The +** result-set expression in all of the following SELECT statements is +** considered a column by this function. +** +** SELECT col FROM tbl; +** SELECT (SELECT col FROM tbl; +** SELECT (SELECT col FROM tbl); +** SELECT abc FROM (SELECT col AS abc FROM tbl); +** +** The declaration type for any expression other than a column is NULL. +*/ +static const char *columnType( + NameContext *pNC, + Expr *pExpr, + const char **pzOriginDb, + const char **pzOriginTab, + const char **pzOriginCol +){ + char const *zType = 0; + char const *zOriginDb = 0; + char const *zOriginTab = 0; + char const *zOriginCol = 0; + int j; + if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 0; + + switch( pExpr->op ){ + case TK_AGG_COLUMN: + case TK_COLUMN: { + /* The expression is a column. Locate the table the column is being + ** extracted from in NameContext.pSrcList. This table may be real + ** database table or a subquery. + */ + Table *pTab = 0; /* Table structure column is extracted from */ + Select *pS = 0; /* Select the column is extracted from */ + int iCol = pExpr->iColumn; /* Index of column in pTab */ + testcase( pExpr->op==TK_AGG_COLUMN ); + testcase( pExpr->op==TK_COLUMN ); + while( pNC && !pTab ){ + SrcList *pTabList = pNC->pSrcList; + for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++); + if( j<pTabList->nSrc ){ + pTab = pTabList->a[j].pTab; + pS = pTabList->a[j].pSelect; + }else{ + pNC = pNC->pNext; + } + } + + if( pTab==0 ){ + /* At one time, code such as "SELECT new.x" within a trigger would + ** cause this condition to run. Since then, we have restructured how + ** trigger code is generated and so this condition is no longer + ** possible. However, it can still be true for statements like + ** the following: + ** + ** CREATE TABLE t1(col INTEGER); + ** SELECT (SELECT t1.col) FROM FROM t1; + ** + ** when columnType() is called on the expression "t1.col" in the + ** sub-select. In this case, set the column type to NULL, even + ** though it should really be "INTEGER". + ** + ** This is not a problem, as the column type of "t1.col" is never + ** used. When columnType() is called on the expression + ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT + ** branch below. */ + break; + } + + assert( pTab && pExpr->pTab==pTab ); + if( pS ){ + /* The "table" is actually a sub-select or a view in the FROM clause + ** of the SELECT statement. Return the declaration type and origin + ** data for the result-set column of the sub-select. + */ + if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){ + /* If iCol is less than zero, then the expression requests the + ** rowid of the sub-select or view. This expression is legal (see + ** test case misc2.2.2) - it always evaluates to NULL. + */ + NameContext sNC; + Expr *p = pS->pEList->a[iCol].pExpr; + sNC.pSrcList = pS->pSrc; + sNC.pNext = pNC; + sNC.pParse = pNC->pParse; + zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol); + } + }else if( ALWAYS(pTab->pSchema) ){ + /* A real table */ + assert( !pS ); + if( iCol<0 ) iCol = pTab->iPKey; + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); + if( iCol<0 ){ + zType = "INTEGER"; + zOriginCol = "rowid"; + }else{ + zType = pTab->aCol[iCol].zType; + zOriginCol = pTab->aCol[iCol].zName; + } + zOriginTab = pTab->zName; + if( pNC->pParse ){ + int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema); + zOriginDb = pNC->pParse->db->aDb[iDb].zName; + } + } + break; + } +#ifndef SQLITE_OMIT_SUBQUERY + case TK_SELECT: { + /* The expression is a sub-select. Return the declaration type and + ** origin info for the single column in the result set of the SELECT + ** statement. + */ + NameContext sNC; + Select *pS = pExpr->x.pSelect; + Expr *p = pS->pEList->a[0].pExpr; + assert( ExprHasProperty(pExpr, EP_xIsSelect) ); + sNC.pSrcList = pS->pSrc; + sNC.pNext = pNC; + sNC.pParse = pNC->pParse; + zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol); + break; + } +#endif + } + + if( pzOriginDb ){ + assert( pzOriginTab && pzOriginCol ); + *pzOriginDb = zOriginDb; + *pzOriginTab = zOriginTab; + *pzOriginCol = zOriginCol; + } + return zType; +} + +/* +** Generate code that will tell the VDBE the declaration types of columns +** in the result set. +*/ +static void generateColumnTypes( + Parse *pParse, /* Parser context */ + SrcList *pTabList, /* List of tables */ + ExprList *pEList /* Expressions defining the result set */ +){ +#ifndef SQLITE_OMIT_DECLTYPE + Vdbe *v = pParse->pVdbe; + int i; + NameContext sNC; + sNC.pSrcList = pTabList; + sNC.pParse = pParse; + for(i=0; i<pEList->nExpr; i++){ + Expr *p = pEList->a[i].pExpr; + const char *zType; +#ifdef SQLITE_ENABLE_COLUMN_METADATA + const char *zOrigDb = 0; + const char *zOrigTab = 0; + const char *zOrigCol = 0; + zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol); + + /* The vdbe must make its own copy of the column-type and other + ** column specific strings, in case the schema is reset before this + ** virtual machine is deleted. + */ + sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT); + sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT); + sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT); +#else + zType = columnType(&sNC, p, 0, 0, 0); +#endif + sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT); + } +#endif /* SQLITE_OMIT_DECLTYPE */ +} + +/* +** Generate code that will tell the VDBE the names of columns +** in the result set. This information is used to provide the +** azCol[] values in the callback. +*/ +static void generateColumnNames( + Parse *pParse, /* Parser context */ + SrcList *pTabList, /* List of tables */ + ExprList *pEList /* Expressions defining the result set */ +){ + Vdbe *v = pParse->pVdbe; + int i, j; + sqlite3 *db = pParse->db; + int fullNames, shortNames; + +#ifndef SQLITE_OMIT_EXPLAIN + /* If this is an EXPLAIN, skip this step */ + if( pParse->explain ){ + return; + } +#endif + + if( pParse->colNamesSet || NEVER(v==0) || db->mallocFailed ) return; + pParse->colNamesSet = 1; + fullNames = (db->flags & SQLITE_FullColNames)!=0; + shortNames = (db->flags & SQLITE_ShortColNames)!=0; + sqlite3VdbeSetNumCols(v, pEList->nExpr); + for(i=0; i<pEList->nExpr; i++){ + Expr *p; + p = pEList->a[i].pExpr; + if( NEVER(p==0) ) continue; + if( pEList->a[i].zName ){ + char *zName = pEList->a[i].zName; + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT); + }else if( (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) && pTabList ){ + Table *pTab; + char *zCol; + int iCol = p->iColumn; + for(j=0; ALWAYS(j<pTabList->nSrc); j++){ + if( pTabList->a[j].iCursor==p->iTable ) break; + } + assert( j<pTabList->nSrc ); + pTab = pTabList->a[j].pTab; + if( iCol<0 ) iCol = pTab->iPKey; + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); + if( iCol<0 ){ + zCol = "rowid"; + }else{ + zCol = pTab->aCol[iCol].zName; + } + if( !shortNames && !fullNames ){ + sqlite3VdbeSetColName(v, i, COLNAME_NAME, + sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC); + }else if( fullNames ){ + char *zName = 0; + zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol); + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC); + }else{ + sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT); + } + }else{ + sqlite3VdbeSetColName(v, i, COLNAME_NAME, + sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC); + } + } + generateColumnTypes(pParse, pTabList, pEList); +} + +/* +** Given a an expression list (which is really the list of expressions +** that form the result set of a SELECT statement) compute appropriate +** column names for a table that would hold the expression list. +** +** All column names will be unique. +** +** Only the column names are computed. Column.zType, Column.zColl, +** and other fields of Column are zeroed. +** +** Return SQLITE_OK on success. If a memory allocation error occurs, +** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM. +*/ +static int selectColumnsFromExprList( + Parse *pParse, /* Parsing context */ + ExprList *pEList, /* Expr list from which to derive column names */ + int *pnCol, /* Write the number of columns here */ + Column **paCol /* Write the new column list here */ +){ + sqlite3 *db = pParse->db; /* Database connection */ + int i, j; /* Loop counters */ + int cnt; /* Index added to make the name unique */ + Column *aCol, *pCol; /* For looping over result columns */ + int nCol; /* Number of columns in the result set */ + Expr *p; /* Expression for a single result column */ + char *zName; /* Column name */ + int nName; /* Size of name in zName[] */ + + *pnCol = nCol = pEList->nExpr; + aCol = *paCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol); + if( aCol==0 ) return SQLITE_NOMEM; + for(i=0, pCol=aCol; i<nCol; i++, pCol++){ + /* Get an appropriate name for the column + */ + p = pEList->a[i].pExpr; + assert( p->pRight==0 || ExprHasProperty(p->pRight, EP_IntValue) + || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 ); + if( (zName = pEList->a[i].zName)!=0 ){ + /* If the column contains an "AS <name>" phrase, use <name> as the name */ + zName = sqlite3DbStrDup(db, zName); + }else{ + Expr *pColExpr = p; /* The expression that is the result column name */ + Table *pTab; /* Table associated with this expression */ + while( pColExpr->op==TK_DOT ){ + pColExpr = pColExpr->pRight; + assert( pColExpr!=0 ); + } + if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){ + /* For columns use the column name name */ + int iCol = pColExpr->iColumn; + pTab = pColExpr->pTab; + if( iCol<0 ) iCol = pTab->iPKey; + zName = sqlite3MPrintf(db, "%s", + iCol>=0 ? pTab->aCol[iCol].zName : "rowid"); + }else if( pColExpr->op==TK_ID ){ + assert( !ExprHasProperty(pColExpr, EP_IntValue) ); + zName = sqlite3MPrintf(db, "%s", pColExpr->u.zToken); + }else{ + /* Use the original text of the column expression as its name */ + zName = sqlite3MPrintf(db, "%s", pEList->a[i].zSpan); + } + } + if( db->mallocFailed ){ + sqlite3DbFree(db, zName); + break; + } + + /* Make sure the column name is unique. If the name is not unique, + ** append a integer to the name so that it becomes unique. + */ + nName = sqlite3Strlen30(zName); + for(j=cnt=0; j<i; j++){ + if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){ + char *zNewName; + zName[nName] = 0; + zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt); + sqlite3DbFree(db, zName); + zName = zNewName; + j = -1; + if( zName==0 ) break; + } + } + pCol->zName = zName; + } + if( db->mallocFailed ){ + for(j=0; j<i; j++){ + sqlite3DbFree(db, aCol[j].zName); + } + sqlite3DbFree(db, aCol); + *paCol = 0; + *pnCol = 0; + return SQLITE_NOMEM; + } + return SQLITE_OK; +} + +/* +** Add type and collation information to a column list based on +** a SELECT statement. +** +** The column list presumably came from selectColumnNamesFromExprList(). +** The column list has only names, not types or collations. This +** routine goes through and adds the types and collations. +** +** This routine requires that all identifiers in the SELECT +** statement be resolved. +*/ +static void selectAddColumnTypeAndCollation( + Parse *pParse, /* Parsing contexts */ + int nCol, /* Number of columns */ + Column *aCol, /* List of columns */ + Select *pSelect /* SELECT used to determine types and collations */ +){ + sqlite3 *db = pParse->db; + NameContext sNC; + Column *pCol; + CollSeq *pColl; + int i; + Expr *p; + struct ExprList_item *a; + + assert( pSelect!=0 ); + assert( (pSelect->selFlags & SF_Resolved)!=0 ); + assert( nCol==pSelect->pEList->nExpr || db->mallocFailed ); + if( db->mallocFailed ) return; + memset(&sNC, 0, sizeof(sNC)); + sNC.pSrcList = pSelect->pSrc; + a = pSelect->pEList->a; + for(i=0, pCol=aCol; i<nCol; i++, pCol++){ + p = a[i].pExpr; + pCol->zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0)); + pCol->affinity = sqlite3ExprAffinity(p); + if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_NONE; + pColl = sqlite3ExprCollSeq(pParse, p); + if( pColl ){ + pCol->zColl = sqlite3DbStrDup(db, pColl->zName); + } + } +} + +/* +** Given a SELECT statement, generate a Table structure that describes +** the result set of that SELECT. +*/ +Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){ + Table *pTab; + sqlite3 *db = pParse->db; + int savedFlags; + + savedFlags = db->flags; + db->flags &= ~SQLITE_FullColNames; + db->flags |= SQLITE_ShortColNames; + sqlite3SelectPrep(pParse, pSelect, 0); + if( pParse->nErr ) return 0; + while( pSelect->pPrior ) pSelect = pSelect->pPrior; + db->flags = savedFlags; + pTab = sqlite3DbMallocZero(db, sizeof(Table) ); + if( pTab==0 ){ + return 0; + } + /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside + ** is disabled */ + assert( db->lookaside.bEnabled==0 ); + pTab->nRef = 1; + pTab->zName = 0; + pTab->nRowEst = 1000000; + selectColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol); + selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSelect); + pTab->iPKey = -1; + if( db->mallocFailed ){ + sqlite3DeleteTable(db, pTab); + return 0; + } + return pTab; +} + +/* +** Get a VDBE for the given parser context. Create a new one if necessary. +** If an error occurs, return NULL and leave a message in pParse. +*/ +Vdbe *sqlite3GetVdbe(Parse *pParse){ + Vdbe *v = pParse->pVdbe; + if( v==0 ){ + v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db); +#ifndef SQLITE_OMIT_TRACE + if( v ){ + sqlite3VdbeAddOp0(v, OP_Trace); + } +#endif + } + return v; +} + + +/* +** Compute the iLimit and iOffset fields of the SELECT based on the +** pLimit and pOffset expressions. pLimit and pOffset hold the expressions +** that appear in the original SQL statement after the LIMIT and OFFSET +** keywords. Or NULL if those keywords are omitted. iLimit and iOffset +** are the integer memory register numbers for counters used to compute +** the limit and offset. If there is no limit and/or offset, then +** iLimit and iOffset are negative. +** +** This routine changes the values of iLimit and iOffset only if +** a limit or offset is defined by pLimit and pOffset. iLimit and +** iOffset should have been preset to appropriate default values +** (usually but not always -1) prior to calling this routine. +** Only if pLimit!=0 or pOffset!=0 do the limit registers get +** redefined. The UNION ALL operator uses this property to force +** the reuse of the same limit and offset registers across multiple +** SELECT statements. +*/ +static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){ + Vdbe *v = 0; + int iLimit = 0; + int iOffset; + int addr1, n; + if( p->iLimit ) return; + + /* + ** "LIMIT -1" always shows all rows. There is some + ** contraversy about what the correct behavior should be. + ** The current implementation interprets "LIMIT 0" to mean + ** no rows. + */ + sqlite3ExprCacheClear(pParse); + assert( p->pOffset==0 || p->pLimit!=0 ); + if( p->pLimit ){ + p->iLimit = iLimit = ++pParse->nMem; + v = sqlite3GetVdbe(pParse); + if( NEVER(v==0) ) return; /* VDBE should have already been allocated */ + if( sqlite3ExprIsInteger(p->pLimit, &n) ){ + sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit); + VdbeComment((v, "LIMIT counter")); + if( n==0 ){ + sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak); + }else{ + if( p->nSelectRow > (double)n ) p->nSelectRow = (double)n; + } + }else{ + sqlite3ExprCode(pParse, p->pLimit, iLimit); + sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); + VdbeComment((v, "LIMIT counter")); + sqlite3VdbeAddOp2(v, OP_IfZero, iLimit, iBreak); + } + if( p->pOffset ){ + p->iOffset = iOffset = ++pParse->nMem; + pParse->nMem++; /* Allocate an extra register for limit+offset */ + sqlite3ExprCode(pParse, p->pOffset, iOffset); + sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); + VdbeComment((v, "OFFSET counter")); + addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iOffset); + sqlite3VdbeAddOp2(v, OP_Integer, 0, iOffset); + sqlite3VdbeJumpHere(v, addr1); + sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1); + VdbeComment((v, "LIMIT+OFFSET")); + addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iLimit); + sqlite3VdbeAddOp2(v, OP_Integer, -1, iOffset+1); + sqlite3VdbeJumpHere(v, addr1); + } + } +} + +#ifndef SQLITE_OMIT_COMPOUND_SELECT +/* +** Return the appropriate collating sequence for the iCol-th column of +** the result set for the compound-select statement "p". Return NULL if +** the column has no default collating sequence. +** +** The collating sequence for the compound select is taken from the +** left-most term of the select that has a collating sequence. +*/ +static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){ + CollSeq *pRet; + if( p->pPrior ){ + pRet = multiSelectCollSeq(pParse, p->pPrior, iCol); + }else{ + pRet = 0; + } + assert( iCol>=0 ); + if( pRet==0 && iCol<p->pEList->nExpr ){ + pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr); + } + return pRet; +} +#endif /* SQLITE_OMIT_COMPOUND_SELECT */ + +/* Forward reference */ +static int multiSelectOrderBy( + Parse *pParse, /* Parsing context */ + Select *p, /* The right-most of SELECTs to be coded */ + SelectDest *pDest /* What to do with query results */ +); + + +#ifndef SQLITE_OMIT_COMPOUND_SELECT +/* +** This routine is called to process a compound query form from +** two or more separate queries using UNION, UNION ALL, EXCEPT, or +** INTERSECT +** +** "p" points to the right-most of the two queries. the query on the +** left is p->pPrior. The left query could also be a compound query +** in which case this routine will be called recursively. +** +** The results of the total query are to be written into a destination +** of type eDest with parameter iParm. +** +** Example 1: Consider a three-way compound SQL statement. +** +** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3 +** +** This statement is parsed up as follows: +** +** SELECT c FROM t3 +** | +** `-----> SELECT b FROM t2 +** | +** `------> SELECT a FROM t1 +** +** The arrows in the diagram above represent the Select.pPrior pointer. +** So if this routine is called with p equal to the t3 query, then +** pPrior will be the t2 query. p->op will be TK_UNION in this case. +** +** Notice that because of the way SQLite parses compound SELECTs, the +** individual selects always group from left to right. +*/ +static int multiSelect( + Parse *pParse, /* Parsing context */ + Select *p, /* The right-most of SELECTs to be coded */ + SelectDest *pDest /* What to do with query results */ +){ + int rc = SQLITE_OK; /* Success code from a subroutine */ + Select *pPrior; /* Another SELECT immediately to our left */ + Vdbe *v; /* Generate code to this VDBE */ + SelectDest dest; /* Alternative data destination */ + Select *pDelete = 0; /* Chain of simple selects to delete */ + sqlite3 *db; /* Database connection */ +#ifndef SQLITE_OMIT_EXPLAIN + int iSub1; /* EQP id of left-hand query */ + int iSub2; /* EQP id of right-hand query */ +#endif + + /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only + ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT. + */ + assert( p && p->pPrior ); /* Calling function guarantees this much */ + db = pParse->db; + pPrior = p->pPrior; + assert( pPrior->pRightmost!=pPrior ); + assert( pPrior->pRightmost==p->pRightmost ); + dest = *pDest; + if( pPrior->pOrderBy ){ + sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before", + selectOpName(p->op)); + rc = 1; + goto multi_select_end; + } + if( pPrior->pLimit ){ + sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before", + selectOpName(p->op)); + rc = 1; + goto multi_select_end; + } + + v = sqlite3GetVdbe(pParse); + assert( v!=0 ); /* The VDBE already created by calling function */ + + /* Create the destination temporary table if necessary + */ + if( dest.eDest==SRT_EphemTab ){ + assert( p->pEList ); + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iParm, p->pEList->nExpr); + sqlite3VdbeChangeP5(v, BTREE_UNORDERED); + dest.eDest = SRT_Table; + } + + /* Make sure all SELECTs in the statement have the same number of elements + ** in their result sets. + */ + assert( p->pEList && pPrior->pEList ); + if( p->pEList->nExpr!=pPrior->pEList->nExpr ){ + sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s" + " do not have the same number of result columns", selectOpName(p->op)); + rc = 1; + goto multi_select_end; + } + + /* Compound SELECTs that have an ORDER BY clause are handled separately. + */ + if( p->pOrderBy ){ + return multiSelectOrderBy(pParse, p, pDest); + } + + /* Generate code for the left and right SELECT statements. + */ + switch( p->op ){ + case TK_ALL: { + int addr = 0; + int nLimit; + assert( !pPrior->pLimit ); + pPrior->pLimit = p->pLimit; + pPrior->pOffset = p->pOffset; + explainSetInteger(iSub1, pParse->iNextSelectId); + rc = sqlite3Select(pParse, pPrior, &dest); + p->pLimit = 0; + p->pOffset = 0; + if( rc ){ + goto multi_select_end; + } + p->pPrior = 0; + p->iLimit = pPrior->iLimit; + p->iOffset = pPrior->iOffset; + if( p->iLimit ){ + addr = sqlite3VdbeAddOp1(v, OP_IfZero, p->iLimit); + VdbeComment((v, "Jump ahead if LIMIT reached")); + } + explainSetInteger(iSub2, pParse->iNextSelectId); + rc = sqlite3Select(pParse, p, &dest); + testcase( rc!=SQLITE_OK ); + pDelete = p->pPrior; + p->pPrior = pPrior; + p->nSelectRow += pPrior->nSelectRow; + if( pPrior->pLimit + && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit) + && p->nSelectRow > (double)nLimit + ){ + p->nSelectRow = (double)nLimit; + } + if( addr ){ + sqlite3VdbeJumpHere(v, addr); + } + break; + } + case TK_EXCEPT: + case TK_UNION: { + int unionTab; /* Cursor number of the temporary table holding result */ + u8 op = 0; /* One of the SRT_ operations to apply to self */ + int priorOp; /* The SRT_ operation to apply to prior selects */ + Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */ + int addr; + SelectDest uniondest; + + testcase( p->op==TK_EXCEPT ); + testcase( p->op==TK_UNION ); + priorOp = SRT_Union; + if( dest.eDest==priorOp && ALWAYS(!p->pLimit &&!p->pOffset) ){ + /* We can reuse a temporary table generated by a SELECT to our + ** right. + */ + assert( p->pRightmost!=p ); /* Can only happen for leftward elements + ** of a 3-way or more compound */ + assert( p->pLimit==0 ); /* Not allowed on leftward elements */ + assert( p->pOffset==0 ); /* Not allowed on leftward elements */ + unionTab = dest.iParm; + }else{ + /* We will need to create our own temporary table to hold the + ** intermediate results. + */ + unionTab = pParse->nTab++; + assert( p->pOrderBy==0 ); + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0); + assert( p->addrOpenEphm[0] == -1 ); + p->addrOpenEphm[0] = addr; + p->pRightmost->selFlags |= SF_UsesEphemeral; + assert( p->pEList ); + } + + /* Code the SELECT statements to our left + */ + assert( !pPrior->pOrderBy ); + sqlite3SelectDestInit(&uniondest, priorOp, unionTab); + explainSetInteger(iSub1, pParse->iNextSelectId); + rc = sqlite3Select(pParse, pPrior, &uniondest); + if( rc ){ + goto multi_select_end; + } + + /* Code the current SELECT statement + */ + if( p->op==TK_EXCEPT ){ + op = SRT_Except; + }else{ + assert( p->op==TK_UNION ); + op = SRT_Union; + } + p->pPrior = 0; + pLimit = p->pLimit; + p->pLimit = 0; + pOffset = p->pOffset; + p->pOffset = 0; + uniondest.eDest = op; + explainSetInteger(iSub2, pParse->iNextSelectId); + rc = sqlite3Select(pParse, p, &uniondest); + testcase( rc!=SQLITE_OK ); + /* Query flattening in sqlite3Select() might refill p->pOrderBy. + ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */ + sqlite3ExprListDelete(db, p->pOrderBy); + pDelete = p->pPrior; + p->pPrior = pPrior; + p->pOrderBy = 0; + if( p->op==TK_UNION ) p->nSelectRow += pPrior->nSelectRow; + sqlite3ExprDelete(db, p->pLimit); + p->pLimit = pLimit; + p->pOffset = pOffset; + p->iLimit = 0; + p->iOffset = 0; + + /* Convert the data in the temporary table into whatever form + ** it is that we currently need. + */ + assert( unionTab==dest.iParm || dest.eDest!=priorOp ); + if( dest.eDest!=priorOp ){ + int iCont, iBreak, iStart; + assert( p->pEList ); + if( dest.eDest==SRT_Output ){ + Select *pFirst = p; + while( pFirst->pPrior ) pFirst = pFirst->pPrior; + generateColumnNames(pParse, 0, pFirst->pEList); + } + iBreak = sqlite3VdbeMakeLabel(v); + iCont = sqlite3VdbeMakeLabel(v); + computeLimitRegisters(pParse, p, iBreak); + sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); + iStart = sqlite3VdbeCurrentAddr(v); + selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr, + 0, -1, &dest, iCont, iBreak); + sqlite3VdbeResolveLabel(v, iCont); + sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); + sqlite3VdbeResolveLabel(v, iBreak); + sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0); + } + break; + } + default: assert( p->op==TK_INTERSECT ); { + int tab1, tab2; + int iCont, iBreak, iStart; + Expr *pLimit, *pOffset; + int addr; + SelectDest intersectdest; + int r1; + + /* INTERSECT is different from the others since it requires + ** two temporary tables. Hence it has its own case. Begin + ** by allocating the tables we will need. + */ + tab1 = pParse->nTab++; + tab2 = pParse->nTab++; + assert( p->pOrderBy==0 ); + + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0); + assert( p->addrOpenEphm[0] == -1 ); + p->addrOpenEphm[0] = addr; + p->pRightmost->selFlags |= SF_UsesEphemeral; + assert( p->pEList ); + + /* Code the SELECTs to our left into temporary table "tab1". + */ + sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1); + explainSetInteger(iSub1, pParse->iNextSelectId); + rc = sqlite3Select(pParse, pPrior, &intersectdest); + if( rc ){ + goto multi_select_end; + } + + /* Code the current SELECT into temporary table "tab2" + */ + addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0); + assert( p->addrOpenEphm[1] == -1 ); + p->addrOpenEphm[1] = addr; + p->pPrior = 0; + pLimit = p->pLimit; + p->pLimit = 0; + pOffset = p->pOffset; + p->pOffset = 0; + intersectdest.iParm = tab2; + explainSetInteger(iSub2, pParse->iNextSelectId); + rc = sqlite3Select(pParse, p, &intersectdest); + testcase( rc!=SQLITE_OK ); + pDelete = p->pPrior; + p->pPrior = pPrior; + if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; + sqlite3ExprDelete(db, p->pLimit); + p->pLimit = pLimit; + p->pOffset = pOffset; + + /* Generate code to take the intersection of the two temporary + ** tables. + */ + assert( p->pEList ); + if( dest.eDest==SRT_Output ){ + Select *pFirst = p; + while( pFirst->pPrior ) pFirst = pFirst->pPrior; + generateColumnNames(pParse, 0, pFirst->pEList); + } + iBreak = sqlite3VdbeMakeLabel(v); + iCont = sqlite3VdbeMakeLabel(v); + computeLimitRegisters(pParse, p, iBreak); + sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); + r1 = sqlite3GetTempReg(pParse); + iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1); + sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); + sqlite3ReleaseTempReg(pParse, r1); + selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr, + 0, -1, &dest, iCont, iBreak); + sqlite3VdbeResolveLabel(v, iCont); + sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); + sqlite3VdbeResolveLabel(v, iBreak); + sqlite3VdbeAddOp2(v, OP_Close, tab2, 0); + sqlite3VdbeAddOp2(v, OP_Close, tab1, 0); + break; + } + } + + explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL); + + /* Compute collating sequences used by + ** temporary tables needed to implement the compound select. + ** Attach the KeyInfo structure to all temporary tables. + ** + ** This section is run by the right-most SELECT statement only. + ** SELECT statements to the left always skip this part. The right-most + ** SELECT might also skip this part if it has no ORDER BY clause and + ** no temp tables are required. + */ + if( p->selFlags & SF_UsesEphemeral ){ + int i; /* Loop counter */ + KeyInfo *pKeyInfo; /* Collating sequence for the result set */ + Select *pLoop; /* For looping through SELECT statements */ + CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */ + int nCol; /* Number of columns in result set */ + + assert( p->pRightmost==p ); + nCol = p->pEList->nExpr; + pKeyInfo = sqlite3DbMallocZero(db, + sizeof(*pKeyInfo)+nCol*(sizeof(CollSeq*) + 1)); + if( !pKeyInfo ){ + rc = SQLITE_NOMEM; + goto multi_select_end; + } + + pKeyInfo->enc = ENC(db); + pKeyInfo->nField = (u16)nCol; + + for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){ + *apColl = multiSelectCollSeq(pParse, p, i); + if( 0==*apColl ){ + *apColl = db->pDfltColl; + } + } + + for(pLoop=p; pLoop; pLoop=pLoop->pPrior){ + for(i=0; i<2; i++){ + int addr = pLoop->addrOpenEphm[i]; + if( addr<0 ){ + /* If [0] is unused then [1] is also unused. So we can + ** always safely abort as soon as the first unused slot is found */ + assert( pLoop->addrOpenEphm[1]<0 ); + break; + } + sqlite3VdbeChangeP2(v, addr, nCol); + sqlite3VdbeChangeP4(v, addr, (char*)pKeyInfo, P4_KEYINFO); + pLoop->addrOpenEphm[i] = -1; + } + } + sqlite3DbFree(db, pKeyInfo); + } + +multi_select_end: + pDest->iMem = dest.iMem; + pDest->nMem = dest.nMem; + sqlite3SelectDelete(db, pDelete); + return rc; +} +#endif /* SQLITE_OMIT_COMPOUND_SELECT */ + +/* +** Code an output subroutine for a coroutine implementation of a +** SELECT statment. +** +** The data to be output is contained in pIn->iMem. There are +** pIn->nMem columns to be output. pDest is where the output should +** be sent. +** +** regReturn is the number of the register holding the subroutine +** return address. +** +** If regPrev>0 then it is the first register in a vector that +** records the previous output. mem[regPrev] is a flag that is false +** if there has been no previous output. If regPrev>0 then code is +** generated to suppress duplicates. pKeyInfo is used for comparing +** keys. +** +** If the LIMIT found in p->iLimit is reached, jump immediately to +** iBreak. +*/ +static int generateOutputSubroutine( + Parse *pParse, /* Parsing context */ + Select *p, /* The SELECT statement */ + SelectDest *pIn, /* Coroutine supplying data */ + SelectDest *pDest, /* Where to send the data */ + int regReturn, /* The return address register */ + int regPrev, /* Previous result register. No uniqueness if 0 */ + KeyInfo *pKeyInfo, /* For comparing with previous entry */ + int p4type, /* The p4 type for pKeyInfo */ + int iBreak /* Jump here if we hit the LIMIT */ +){ + Vdbe *v = pParse->pVdbe; + int iContinue; + int addr; + + addr = sqlite3VdbeCurrentAddr(v); + iContinue = sqlite3VdbeMakeLabel(v); + + /* Suppress duplicates for UNION, EXCEPT, and INTERSECT + */ + if( regPrev ){ + int j1, j2; + j1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); + j2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iMem, regPrev+1, pIn->nMem, + (char*)pKeyInfo, p4type); + sqlite3VdbeAddOp3(v, OP_Jump, j2+2, iContinue, j2+2); + sqlite3VdbeJumpHere(v, j1); + sqlite3ExprCodeCopy(pParse, pIn->iMem, regPrev+1, pIn->nMem); + sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev); + } + if( pParse->db->mallocFailed ) return 0; + + /* Suppress the the first OFFSET entries if there is an OFFSET clause + */ + codeOffset(v, p, iContinue); + + switch( pDest->eDest ){ + /* Store the result as data using a unique key. + */ + case SRT_Table: + case SRT_EphemTab: { + int r1 = sqlite3GetTempReg(pParse); + int r2 = sqlite3GetTempReg(pParse); + testcase( pDest->eDest==SRT_Table ); + testcase( pDest->eDest==SRT_EphemTab ); + sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iMem, pIn->nMem, r1); + sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iParm, r2); + sqlite3VdbeAddOp3(v, OP_Insert, pDest->iParm, r1, r2); + sqlite3VdbeChangeP5(v, OPFLAG_APPEND); + sqlite3ReleaseTempReg(pParse, r2); + sqlite3ReleaseTempReg(pParse, r1); + break; + } + +#ifndef SQLITE_OMIT_SUBQUERY + /* If we are creating a set for an "expr IN (SELECT ...)" construct, + ** then there should be a single item on the stack. Write this + ** item into the set table with bogus data. + */ + case SRT_Set: { + int r1; + assert( pIn->nMem==1 ); + p->affinity = + sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affinity); + r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iMem, 1, r1, &p->affinity, 1); + sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, 1); + sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iParm, r1); + sqlite3ReleaseTempReg(pParse, r1); + break; + } + +#if 0 /* Never occurs on an ORDER BY query */ + /* If any row exist in the result set, record that fact and abort. + */ + case SRT_Exists: { + sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest->iParm); + /* The LIMIT clause will terminate the loop for us */ + break; + } +#endif + + /* If this is a scalar select that is part of an expression, then + ** store the results in the appropriate memory cell and break out + ** of the scan loop. + */ + case SRT_Mem: { + assert( pIn->nMem==1 ); + sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iParm, 1); + /* The LIMIT clause will jump out of the loop for us */ + break; + } +#endif /* #ifndef SQLITE_OMIT_SUBQUERY */ + + /* The results are stored in a sequence of registers + ** starting at pDest->iMem. Then the co-routine yields. + */ + case SRT_Coroutine: { + if( pDest->iMem==0 ){ + pDest->iMem = sqlite3GetTempRange(pParse, pIn->nMem); + pDest->nMem = pIn->nMem; + } + sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iMem, pDest->nMem); + sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); + break; + } + + /* If none of the above, then the result destination must be + ** SRT_Output. This routine is never called with any other + ** destination other than the ones handled above or SRT_Output. + ** + ** For SRT_Output, results are stored in a sequence of registers. + ** Then the OP_ResultRow opcode is used to cause sqlite3_step() to + ** return the next row of result. + */ + default: { + assert( pDest->eDest==SRT_Output ); + sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iMem, pIn->nMem); + sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, pIn->nMem); + break; + } + } + + /* Jump to the end of the loop if the LIMIT is reached. + */ + if( p->iLimit ){ + sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1); + } + + /* Generate the subroutine return + */ + sqlite3VdbeResolveLabel(v, iContinue); + sqlite3VdbeAddOp1(v, OP_Return, regReturn); + + return addr; +} + +/* +** Alternative compound select code generator for cases when there +** is an ORDER BY clause. +** +** We assume a query of the following form: +** +** <selectA> <operator> <selectB> ORDER BY <orderbylist> +** +** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea +** is to code both <selectA> and <selectB> with the ORDER BY clause as +** co-routines. Then run the co-routines in parallel and merge the results +** into the output. In addition to the two coroutines (called selectA and +** selectB) there are 7 subroutines: +** +** outA: Move the output of the selectA coroutine into the output +** of the compound query. +** +** outB: Move the output of the selectB coroutine into the output +** of the compound query. (Only generated for UNION and +** UNION ALL. EXCEPT and INSERTSECT never output a row that +** appears only in B.) +** +** AltB: Called when there is data from both coroutines and A<B. +** +** AeqB: Called when there is data from both coroutines and A==B. +** +** AgtB: Called when there is data from both coroutines and A>B. +** +** EofA: Called when data is exhausted from selectA. +** +** EofB: Called when data is exhausted from selectB. +** +** The implementation of the latter five subroutines depend on which +** <operator> is used: +** +** +** UNION ALL UNION EXCEPT INTERSECT +** ------------- ----------------- -------------- ----------------- +** AltB: outA, nextA outA, nextA outA, nextA nextA +** +** AeqB: outA, nextA nextA nextA outA, nextA +** +** AgtB: outB, nextB outB, nextB nextB nextB +** +** EofA: outB, nextB outB, nextB halt halt +** +** EofB: outA, nextA outA, nextA outA, nextA halt +** +** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA +** causes an immediate jump to EofA and an EOF on B following nextB causes +** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or +** following nextX causes a jump to the end of the select processing. +** +** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled +** within the output subroutine. The regPrev register set holds the previously +** output value. A comparison is made against this value and the output +** is skipped if the next results would be the same as the previous. +** +** The implementation plan is to implement the two coroutines and seven +** subroutines first, then put the control logic at the bottom. Like this: +** +** goto Init +** coA: coroutine for left query (A) +** coB: coroutine for right query (B) +** outA: output one row of A +** outB: output one row of B (UNION and UNION ALL only) +** EofA: ... +** EofB: ... +** AltB: ... +** AeqB: ... +** AgtB: ... +** Init: initialize coroutine registers +** yield coA +** if eof(A) goto EofA +** yield coB +** if eof(B) goto EofB +** Cmpr: Compare A, B +** Jump AltB, AeqB, AgtB +** End: ... +** +** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not +** actually called using Gosub and they do not Return. EofA and EofB loop +** until all data is exhausted then jump to the "end" labe. AltB, AeqB, +** and AgtB jump to either L2 or to one of EofA or EofB. +*/ +#ifndef SQLITE_OMIT_COMPOUND_SELECT +static int multiSelectOrderBy( + Parse *pParse, /* Parsing context */ + Select *p, /* The right-most of SELECTs to be coded */ + SelectDest *pDest /* What to do with query results */ +){ + int i, j; /* Loop counters */ + Select *pPrior; /* Another SELECT immediately to our left */ + Vdbe *v; /* Generate code to this VDBE */ + SelectDest destA; /* Destination for coroutine A */ + SelectDest destB; /* Destination for coroutine B */ + int regAddrA; /* Address register for select-A coroutine */ + int regEofA; /* Flag to indicate when select-A is complete */ + int regAddrB; /* Address register for select-B coroutine */ + int regEofB; /* Flag to indicate when select-B is complete */ + int addrSelectA; /* Address of the select-A coroutine */ + int addrSelectB; /* Address of the select-B coroutine */ + int regOutA; /* Address register for the output-A subroutine */ + int regOutB; /* Address register for the output-B subroutine */ + int addrOutA; /* Address of the output-A subroutine */ + int addrOutB = 0; /* Address of the output-B subroutine */ + int addrEofA; /* Address of the select-A-exhausted subroutine */ + int addrEofB; /* Address of the select-B-exhausted subroutine */ + int addrAltB; /* Address of the A<B subroutine */ + int addrAeqB; /* Address of the A==B subroutine */ + int addrAgtB; /* Address of the A>B subroutine */ + int regLimitA; /* Limit register for select-A */ + int regLimitB; /* Limit register for select-A */ + int regPrev; /* A range of registers to hold previous output */ + int savedLimit; /* Saved value of p->iLimit */ + int savedOffset; /* Saved value of p->iOffset */ + int labelCmpr; /* Label for the start of the merge algorithm */ + int labelEnd; /* Label for the end of the overall SELECT stmt */ + int j1; /* Jump instructions that get retargetted */ + int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */ + KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */ + KeyInfo *pKeyMerge; /* Comparison information for merging rows */ + sqlite3 *db; /* Database connection */ + ExprList *pOrderBy; /* The ORDER BY clause */ + int nOrderBy; /* Number of terms in the ORDER BY clause */ + int *aPermute; /* Mapping from ORDER BY terms to result set columns */ +#ifndef SQLITE_OMIT_EXPLAIN + int iSub1; /* EQP id of left-hand query */ + int iSub2; /* EQP id of right-hand query */ +#endif + + assert( p->pOrderBy!=0 ); + assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */ + db = pParse->db; + v = pParse->pVdbe; + assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */ + labelEnd = sqlite3VdbeMakeLabel(v); + labelCmpr = sqlite3VdbeMakeLabel(v); + + + /* Patch up the ORDER BY clause + */ + op = p->op; + pPrior = p->pPrior; + assert( pPrior->pOrderBy==0 ); + pOrderBy = p->pOrderBy; + assert( pOrderBy ); + nOrderBy = pOrderBy->nExpr; + + /* For operators other than UNION ALL we have to make sure that + ** the ORDER BY clause covers every term of the result set. Add + ** terms to the ORDER BY clause as necessary. + */ + if( op!=TK_ALL ){ + for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){ + struct ExprList_item *pItem; + for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){ + assert( pItem->iCol>0 ); + if( pItem->iCol==i ) break; + } + if( j==nOrderBy ){ + Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0); + if( pNew==0 ) return SQLITE_NOMEM; + pNew->flags |= EP_IntValue; + pNew->u.iValue = i; + pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew); + pOrderBy->a[nOrderBy++].iCol = (u16)i; + } + } + } + + /* Compute the comparison permutation and keyinfo that is used with + ** the permutation used to determine if the next + ** row of results comes from selectA or selectB. Also add explicit + ** collations to the ORDER BY clause terms so that when the subqueries + ** to the right and the left are evaluated, they use the correct + ** collation. + */ + aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy); + if( aPermute ){ + struct ExprList_item *pItem; + for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){ + assert( pItem->iCol>0 && pItem->iCol<=p->pEList->nExpr ); + aPermute[i] = pItem->iCol - 1; + } + pKeyMerge = + sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq*)+1)); + if( pKeyMerge ){ + pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy]; + pKeyMerge->nField = (u16)nOrderBy; + pKeyMerge->enc = ENC(db); + for(i=0; i<nOrderBy; i++){ + CollSeq *pColl; + Expr *pTerm = pOrderBy->a[i].pExpr; + if( pTerm->flags & EP_ExpCollate ){ + pColl = pTerm->pColl; + }else{ + pColl = multiSelectCollSeq(pParse, p, aPermute[i]); + pTerm->flags |= EP_ExpCollate; + pTerm->pColl = pColl; + } + pKeyMerge->aColl[i] = pColl; + pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder; + } + } + }else{ + pKeyMerge = 0; + } + + /* Reattach the ORDER BY clause to the query. + */ + p->pOrderBy = pOrderBy; + pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0); + + /* Allocate a range of temporary registers and the KeyInfo needed + ** for the logic that removes duplicate result rows when the + ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL). + */ + if( op==TK_ALL ){ + regPrev = 0; + }else{ + int nExpr = p->pEList->nExpr; + assert( nOrderBy>=nExpr || db->mallocFailed ); + regPrev = sqlite3GetTempRange(pParse, nExpr+1); + sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev); + pKeyDup = sqlite3DbMallocZero(db, + sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq*)+1) ); + if( pKeyDup ){ + pKeyDup->aSortOrder = (u8*)&pKeyDup->aColl[nExpr]; + pKeyDup->nField = (u16)nExpr; + pKeyDup->enc = ENC(db); + for(i=0; i<nExpr; i++){ + pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i); + pKeyDup->aSortOrder[i] = 0; + } + } + } + + /* Separate the left and the right query from one another + */ + p->pPrior = 0; + sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER"); + if( pPrior->pPrior==0 ){ + sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER"); + } + + /* Compute the limit registers */ + computeLimitRegisters(pParse, p, labelEnd); + if( p->iLimit && op==TK_ALL ){ + regLimitA = ++pParse->nMem; + regLimitB = ++pParse->nMem; + sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit, + regLimitA); + sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB); + }else{ + regLimitA = regLimitB = 0; + } + sqlite3ExprDelete(db, p->pLimit); + p->pLimit = 0; + sqlite3ExprDelete(db, p->pOffset); + p->pOffset = 0; + + regAddrA = ++pParse->nMem; + regEofA = ++pParse->nMem; + regAddrB = ++pParse->nMem; + regEofB = ++pParse->nMem; + regOutA = ++pParse->nMem; + regOutB = ++pParse->nMem; + sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA); + sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB); + + /* Jump past the various subroutines and coroutines to the main + ** merge loop + */ + j1 = sqlite3VdbeAddOp0(v, OP_Goto); + addrSelectA = sqlite3VdbeCurrentAddr(v); + + + /* Generate a coroutine to evaluate the SELECT statement to the + ** left of the compound operator - the "A" select. + */ + VdbeNoopComment((v, "Begin coroutine for left SELECT")); + pPrior->iLimit = regLimitA; + explainSetInteger(iSub1, pParse->iNextSelectId); + sqlite3Select(pParse, pPrior, &destA); + sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA); + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); + VdbeNoopComment((v, "End coroutine for left SELECT")); + + /* Generate a coroutine to evaluate the SELECT statement on + ** the right - the "B" select + */ + addrSelectB = sqlite3VdbeCurrentAddr(v); + VdbeNoopComment((v, "Begin coroutine for right SELECT")); + savedLimit = p->iLimit; + savedOffset = p->iOffset; + p->iLimit = regLimitB; + p->iOffset = 0; + explainSetInteger(iSub2, pParse->iNextSelectId); + sqlite3Select(pParse, p, &destB); + p->iLimit = savedLimit; + p->iOffset = savedOffset; + sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB); + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); + VdbeNoopComment((v, "End coroutine for right SELECT")); + + /* Generate a subroutine that outputs the current row of the A + ** select as the next output row of the compound select. + */ + VdbeNoopComment((v, "Output routine for A")); + addrOutA = generateOutputSubroutine(pParse, + p, &destA, pDest, regOutA, + regPrev, pKeyDup, P4_KEYINFO_HANDOFF, labelEnd); + + /* Generate a subroutine that outputs the current row of the B + ** select as the next output row of the compound select. + */ + if( op==TK_ALL || op==TK_UNION ){ + VdbeNoopComment((v, "Output routine for B")); + addrOutB = generateOutputSubroutine(pParse, + p, &destB, pDest, regOutB, + regPrev, pKeyDup, P4_KEYINFO_STATIC, labelEnd); + } + + /* Generate a subroutine to run when the results from select A + ** are exhausted and only data in select B remains. + */ + VdbeNoopComment((v, "eof-A subroutine")); + if( op==TK_EXCEPT || op==TK_INTERSECT ){ + addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd); + }else{ + addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd); + sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA); + p->nSelectRow += pPrior->nSelectRow; + } + + /* Generate a subroutine to run when the results from select B + ** are exhausted and only data in select A remains. + */ + if( op==TK_INTERSECT ){ + addrEofB = addrEofA; + if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; + }else{ + VdbeNoopComment((v, "eof-B subroutine")); + addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd); + sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB); + } + + /* Generate code to handle the case of A<B + */ + VdbeNoopComment((v, "A-lt-B subroutine")); + addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA); + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr); + + /* Generate code to handle the case of A==B + */ + if( op==TK_ALL ){ + addrAeqB = addrAltB; + }else if( op==TK_INTERSECT ){ + addrAeqB = addrAltB; + addrAltB++; + }else{ + VdbeNoopComment((v, "A-eq-B subroutine")); + addrAeqB = + sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA); + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr); + } + + /* Generate code to handle the case of A>B + */ + VdbeNoopComment((v, "A-gt-B subroutine")); + addrAgtB = sqlite3VdbeCurrentAddr(v); + if( op==TK_ALL || op==TK_UNION ){ + sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); + } + sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); + sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB); + sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr); + + /* This code runs once to initialize everything. + */ + sqlite3VdbeJumpHere(v, j1); + sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA); + sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB); + sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA); + sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB); + sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA); + sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB); + + /* Implement the main merge loop + */ + sqlite3VdbeResolveLabel(v, labelCmpr); + sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY); + sqlite3VdbeAddOp4(v, OP_Compare, destA.iMem, destB.iMem, nOrderBy, + (char*)pKeyMerge, P4_KEYINFO_HANDOFF); + sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); + + /* Release temporary registers + */ + if( regPrev ){ + sqlite3ReleaseTempRange(pParse, regPrev, nOrderBy+1); + } + + /* Jump to the this point in order to terminate the query. + */ + sqlite3VdbeResolveLabel(v, labelEnd); + + /* Set the number of output columns + */ + if( pDest->eDest==SRT_Output ){ + Select *pFirst = pPrior; + while( pFirst->pPrior ) pFirst = pFirst->pPrior; + generateColumnNames(pParse, 0, pFirst->pEList); + } + + /* Reassembly the compound query so that it will be freed correctly + ** by the calling function */ + if( p->pPrior ){ + sqlite3SelectDelete(db, p->pPrior); + } + p->pPrior = pPrior; + + /*** TBD: Insert subroutine calls to close cursors on incomplete + **** subqueries ****/ + explainComposite(pParse, p->op, iSub1, iSub2, 0); + return SQLITE_OK; +} +#endif + +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) +/* Forward Declarations */ +static void substExprList(sqlite3*, ExprList*, int, ExprList*); +static void substSelect(sqlite3*, Select *, int, ExprList *); + +/* +** Scan through the expression pExpr. Replace every reference to +** a column in table number iTable with a copy of the iColumn-th +** entry in pEList. (But leave references to the ROWID column +** unchanged.) +** +** This routine is part of the flattening procedure. A subquery +** whose result set is defined by pEList appears as entry in the +** FROM clause of a SELECT such that the VDBE cursor assigned to that +** FORM clause entry is iTable. This routine make the necessary +** changes to pExpr so that it refers directly to the source table +** of the subquery rather the result set of the subquery. +*/ +static Expr *substExpr( + sqlite3 *db, /* Report malloc errors to this connection */ + Expr *pExpr, /* Expr in which substitution occurs */ + int iTable, /* Table to be substituted */ + ExprList *pEList /* Substitute expressions */ +){ + if( pExpr==0 ) return 0; + if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){ + if( pExpr->iColumn<0 ){ + pExpr->op = TK_NULL; + }else{ + Expr *pNew; + assert( pEList!=0 && pExpr->iColumn<pEList->nExpr ); + assert( pExpr->pLeft==0 && pExpr->pRight==0 ); + pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0); + if( pNew && pExpr->pColl ){ + pNew->pColl = pExpr->pColl; + } + sqlite3ExprDelete(db, pExpr); + pExpr = pNew; + } + }else{ + pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList); + pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList); + if( ExprHasProperty(pExpr, EP_xIsSelect) ){ + substSelect(db, pExpr->x.pSelect, iTable, pEList); + }else{ + substExprList(db, pExpr->x.pList, iTable, pEList); + } + } + return pExpr; +} +static void substExprList( + sqlite3 *db, /* Report malloc errors here */ + ExprList *pList, /* List to scan and in which to make substitutes */ + int iTable, /* Table to be substituted */ + ExprList *pEList /* Substitute values */ +){ + int i; + if( pList==0 ) return; + for(i=0; i<pList->nExpr; i++){ + pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList); + } +} +static void substSelect( + sqlite3 *db, /* Report malloc errors here */ + Select *p, /* SELECT statement in which to make substitutions */ + int iTable, /* Table to be replaced */ + ExprList *pEList /* Substitute values */ +){ + SrcList *pSrc; + struct SrcList_item *pItem; + int i; + if( !p ) return; + substExprList(db, p->pEList, iTable, pEList); + substExprList(db, p->pGroupBy, iTable, pEList); + substExprList(db, p->pOrderBy, iTable, pEList); + p->pHaving = substExpr(db, p->pHaving, iTable, pEList); + p->pWhere = substExpr(db, p->pWhere, iTable, pEList); + substSelect(db, p->pPrior, iTable, pEList); + pSrc = p->pSrc; + assert( pSrc ); /* Even for (SELECT 1) we have: pSrc!=0 but pSrc->nSrc==0 */ + if( ALWAYS(pSrc) ){ + for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ + substSelect(db, pItem->pSelect, iTable, pEList); + } + } +} +#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ + +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) +/* +** This routine attempts to flatten subqueries in order to speed +** execution. It returns 1 if it makes changes and 0 if no flattening +** occurs. +** +** To understand the concept of flattening, consider the following +** query: +** +** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5 +** +** The default way of implementing this query is to execute the +** subquery first and store the results in a temporary table, then +** run the outer query on that temporary table. This requires two +** passes over the data. Furthermore, because the temporary table +** has no indices, the WHERE clause on the outer query cannot be +** optimized. +** +** This routine attempts to rewrite queries such as the above into +** a single flat select, like this: +** +** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5 +** +** The code generated for this simpification gives the same result +** but only has to scan the data once. And because indices might +** exist on the table t1, a complete scan of the data might be +** avoided. +** +** Flattening is only attempted if all of the following are true: +** +** (1) The subquery and the outer query do not both use aggregates. +** +** (2) The subquery is not an aggregate or the outer query is not a join. +** +** (3) The subquery is not the right operand of a left outer join +** (Originally ticket #306. Strengthened by ticket #3300) +** +** (4) The subquery is not DISTINCT. +** +** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT +** sub-queries that were excluded from this optimization. Restriction +** (4) has since been expanded to exclude all DISTINCT subqueries. +** +** (6) The subquery does not use aggregates or the outer query is not +** DISTINCT. +** +** (7) The subquery has a FROM clause. +** +** (8) The subquery does not use LIMIT or the outer query is not a join. +** +** (9) The subquery does not use LIMIT or the outer query does not use +** aggregates. +** +** (10) The subquery does not use aggregates or the outer query does not +** use LIMIT. +** +** (11) The subquery and the outer query do not both have ORDER BY clauses. +** +** (**) Not implemented. Subsumed into restriction (3). Was previously +** a separate restriction deriving from ticket #350. +** +** (13) The subquery and outer query do not both use LIMIT. +** +** (14) The subquery does not use OFFSET. +** +** (15) The outer query is not part of a compound select or the +** subquery does not have a LIMIT clause. +** (See ticket #2339 and ticket [02a8e81d44]). +** +** (16) The outer query is not an aggregate or the subquery does +** not contain ORDER BY. (Ticket #2942) This used to not matter +** until we introduced the group_concat() function. +** +** (17) The sub-query is not a compound select, or it is a UNION ALL +** compound clause made up entirely of non-aggregate queries, and +** the parent query: +** +** * is not itself part of a compound select, +** * is not an aggregate or DISTINCT query, and +** * has no other tables or sub-selects in the FROM clause. +** +** The parent and sub-query may contain WHERE clauses. Subject to +** rules (11), (13) and (14), they may also contain ORDER BY, +** LIMIT and OFFSET clauses. +** +** (18) If the sub-query is a compound select, then all terms of the +** ORDER by clause of the parent must be simple references to +** columns of the sub-query. +** +** (19) The subquery does not use LIMIT or the outer query does not +** have a WHERE clause. +** +** (20) If the sub-query is a compound select, then it must not use +** an ORDER BY clause. Ticket #3773. We could relax this constraint +** somewhat by saying that the terms of the ORDER BY clause must +** appear as unmodified result columns in the outer query. But +** have other optimizations in mind to deal with that case. +** +** (21) The subquery does not use LIMIT or the outer query is not +** DISTINCT. (See ticket [752e1646fc]). +** +** In this routine, the "p" parameter is a pointer to the outer query. +** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query +** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. +** +** If flattening is not attempted, this routine is a no-op and returns 0. +** If flattening is attempted this routine returns 1. +** +** All of the expression analysis must occur on both the outer query and +** the subquery before this routine runs. +*/ +static int flattenSubquery( + Parse *pParse, /* Parsing context */ + Select *p, /* The parent or outer SELECT statement */ + int iFrom, /* Index in p->pSrc->a[] of the inner subquery */ + int isAgg, /* True if outer SELECT uses aggregate functions */ + int subqueryIsAgg /* True if the subquery uses aggregate functions */ +){ + const char *zSavedAuthContext = pParse->zAuthContext; + Select *pParent; + Select *pSub; /* The inner query or "subquery" */ + Select *pSub1; /* Pointer to the rightmost select in sub-query */ + SrcList *pSrc; /* The FROM clause of the outer query */ + SrcList *pSubSrc; /* The FROM clause of the subquery */ + ExprList *pList; /* The result set of the outer query */ + int iParent; /* VDBE cursor number of the pSub result set temp table */ + int i; /* Loop counter */ + Expr *pWhere; /* The WHERE clause */ + struct SrcList_item *pSubitem; /* The subquery */ + sqlite3 *db = pParse->db; + + /* Check to see if flattening is permitted. Return 0 if not. + */ + assert( p!=0 ); + assert( p->pPrior==0 ); /* Unable to flatten compound queries */ + if( db->flags & SQLITE_QueryFlattener ) return 0; + pSrc = p->pSrc; + assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc ); + pSubitem = &pSrc->a[iFrom]; + iParent = pSubitem->iCursor; + pSub = pSubitem->pSelect; + assert( pSub!=0 ); + if( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */ + if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */ + pSubSrc = pSub->pSrc; + assert( pSubSrc ); + /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants, + ** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET + ** because they could be computed at compile-time. But when LIMIT and OFFSET + ** became arbitrary expressions, we were forced to add restrictions (13) + ** and (14). */ + if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */ + if( pSub->pOffset ) return 0; /* Restriction (14) */ + if( p->pRightmost && pSub->pLimit ){ + return 0; /* Restriction (15) */ + } + if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */ + if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (5) */ + if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){ + return 0; /* Restrictions (8)(9) */ + } + if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){ + return 0; /* Restriction (6) */ + } + if( p->pOrderBy && pSub->pOrderBy ){ + return 0; /* Restriction (11) */ + } + if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */ + if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */ + if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){ + return 0; /* Restriction (21) */ + } + + /* OBSOLETE COMMENT 1: + ** Restriction 3: If the subquery is a join, make sure the subquery is + ** not used as the right operand of an outer join. Examples of why this + ** is not allowed: + ** + ** t1 LEFT OUTER JOIN (t2 JOIN t3) + ** + ** If we flatten the above, we would get + ** + ** (t1 LEFT OUTER JOIN t2) JOIN t3 + ** + ** which is not at all the same thing. + ** + ** OBSOLETE COMMENT 2: + ** Restriction 12: If the subquery is the right operand of a left outer + ** join, make sure the subquery has no WHERE clause. + ** An examples of why this is not allowed: + ** + ** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0) + ** + ** If we flatten the above, we would get + ** + ** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0 + ** + ** But the t2.x>0 test will always fail on a NULL row of t2, which + ** effectively converts the OUTER JOIN into an INNER JOIN. + ** + ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE: + ** Ticket #3300 shows that flattening the right term of a LEFT JOIN + ** is fraught with danger. Best to avoid the whole thing. If the + ** subquery is the right term of a LEFT JOIN, then do not flatten. + */ + if( (pSubitem->jointype & JT_OUTER)!=0 ){ + return 0; + } + + /* Restriction 17: If the sub-query is a compound SELECT, then it must + ** use only the UNION ALL operator. And none of the simple select queries + ** that make up the compound SELECT are allowed to be aggregate or distinct + ** queries. + */ + if( pSub->pPrior ){ + if( pSub->pOrderBy ){ + return 0; /* Restriction 20 */ + } + if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){ + return 0; + } + for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){ + testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ); + testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate ); + if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 + || (pSub1->pPrior && pSub1->op!=TK_ALL) + || NEVER(pSub1->pSrc==0) || pSub1->pSrc->nSrc!=1 + ){ + return 0; + } + } + + /* Restriction 18. */ + if( p->pOrderBy ){ + int ii; + for(ii=0; ii<p->pOrderBy->nExpr; ii++){ + if( p->pOrderBy->a[ii].iCol==0 ) return 0; + } + } + } + + /***** If we reach this point, flattening is permitted. *****/ + + /* Authorize the subquery */ + pParse->zAuthContext = pSubitem->zName; + sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0); + pParse->zAuthContext = zSavedAuthContext; + + /* If the sub-query is a compound SELECT statement, then (by restrictions + ** 17 and 18 above) it must be a UNION ALL and the parent query must + ** be of the form: + ** + ** SELECT <expr-list> FROM (<sub-query>) <where-clause> + ** + ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block + ** creates N-1 copies of the parent query without any ORDER BY, LIMIT or + ** OFFSET clauses and joins them to the left-hand-side of the original + ** using UNION ALL operators. In this case N is the number of simple + ** select statements in the compound sub-query. + ** + ** Example: + ** + ** SELECT a+1 FROM ( + ** SELECT x FROM tab + ** UNION ALL + ** SELECT y FROM tab + ** UNION ALL + ** SELECT abs(z*2) FROM tab2 + ** ) WHERE a!=5 ORDER BY 1 + ** + ** Transformed into: + ** + ** SELECT x+1 FROM tab WHERE x+1!=5 + ** UNION ALL + ** SELECT y+1 FROM tab WHERE y+1!=5 + ** UNION ALL + ** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5 + ** ORDER BY 1 + ** + ** We call this the "compound-subquery flattening". + */ + for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){ + Select *pNew; + ExprList *pOrderBy = p->pOrderBy; + Expr *pLimit = p->pLimit; + Select *pPrior = p->pPrior; + p->pOrderBy = 0; + p->pSrc = 0; + p->pPrior = 0; + p->pLimit = 0; + pNew = sqlite3SelectDup(db, p, 0); + p->pLimit = pLimit; + p->pOrderBy = pOrderBy; + p->pSrc = pSrc; + p->op = TK_ALL; + p->pRightmost = 0; + if( pNew==0 ){ + pNew = pPrior; + }else{ + pNew->pPrior = pPrior; + pNew->pRightmost = 0; + } + p->pPrior = pNew; + if( db->mallocFailed ) return 1; + } + + /* Begin flattening the iFrom-th entry of the FROM clause + ** in the outer query. + */ + pSub = pSub1 = pSubitem->pSelect; + + /* Delete the transient table structure associated with the + ** subquery + */ + sqlite3DbFree(db, pSubitem->zDatabase); + sqlite3DbFree(db, pSubitem->zName); + sqlite3DbFree(db, pSubitem->zAlias); + pSubitem->zDatabase = 0; + pSubitem->zName = 0; + pSubitem->zAlias = 0; + pSubitem->pSelect = 0; + + /* Defer deleting the Table object associated with the + ** subquery until code generation is + ** complete, since there may still exist Expr.pTab entries that + ** refer to the subquery even after flattening. Ticket #3346. + ** + ** pSubitem->pTab is always non-NULL by test restrictions and tests above. + */ + if( ALWAYS(pSubitem->pTab!=0) ){ + Table *pTabToDel = pSubitem->pTab; + if( pTabToDel->nRef==1 ){ + Parse *pToplevel = sqlite3ParseToplevel(pParse); + pTabToDel->pNextZombie = pToplevel->pZombieTab; + pToplevel->pZombieTab = pTabToDel; + }else{ + pTabToDel->nRef--; + } + pSubitem->pTab = 0; + } + + /* The following loop runs once for each term in a compound-subquery + ** flattening (as described above). If we are doing a different kind + ** of flattening - a flattening other than a compound-subquery flattening - + ** then this loop only runs once. + ** + ** This loop moves all of the FROM elements of the subquery into the + ** the FROM clause of the outer query. Before doing this, remember + ** the cursor number for the original outer query FROM element in + ** iParent. The iParent cursor will never be used. Subsequent code + ** will scan expressions looking for iParent references and replace + ** those references with expressions that resolve to the subquery FROM + ** elements we are now copying in. + */ + for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){ + int nSubSrc; + u8 jointype = 0; + pSubSrc = pSub->pSrc; /* FROM clause of subquery */ + nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */ + pSrc = pParent->pSrc; /* FROM clause of the outer query */ + + if( pSrc ){ + assert( pParent==p ); /* First time through the loop */ + jointype = pSubitem->jointype; + }else{ + assert( pParent!=p ); /* 2nd and subsequent times through the loop */ + pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0); + if( pSrc==0 ){ + assert( db->mallocFailed ); + break; + } + } + + /* The subquery uses a single slot of the FROM clause of the outer + ** query. If the subquery has more than one element in its FROM clause, + ** then expand the outer query to make space for it to hold all elements + ** of the subquery. + ** + ** Example: + ** + ** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB; + ** + ** The outer query has 3 slots in its FROM clause. One slot of the + ** outer query (the middle slot) is used by the subquery. The next + ** block of code will expand the out query to 4 slots. The middle + ** slot is expanded to two slots in order to make space for the + ** two elements in the FROM clause of the subquery. + */ + if( nSubSrc>1 ){ + pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1); + if( db->mallocFailed ){ + break; + } + } + + /* Transfer the FROM clause terms from the subquery into the + ** outer query. + */ + for(i=0; i<nSubSrc; i++){ + sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing); + pSrc->a[i+iFrom] = pSubSrc->a[i]; + memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); + } + pSrc->a[iFrom].jointype = jointype; + + /* Now begin substituting subquery result set expressions for + ** references to the iParent in the outer query. + ** + ** Example: + ** + ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b; + ** \ \_____________ subquery __________/ / + ** \_____________________ outer query ______________________________/ + ** + ** We look at every expression in the outer query and every place we see + ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10". + */ + pList = pParent->pEList; + for(i=0; i<pList->nExpr; i++){ + if( pList->a[i].zName==0 ){ + const char *zSpan = pList->a[i].zSpan; + if( ALWAYS(zSpan) ){ + pList->a[i].zName = sqlite3DbStrDup(db, zSpan); + } + } + } + substExprList(db, pParent->pEList, iParent, pSub->pEList); + if( isAgg ){ + substExprList(db, pParent->pGroupBy, iParent, pSub->pEList); + pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList); + } + if( pSub->pOrderBy ){ + assert( pParent->pOrderBy==0 ); + pParent->pOrderBy = pSub->pOrderBy; + pSub->pOrderBy = 0; + }else if( pParent->pOrderBy ){ + substExprList(db, pParent->pOrderBy, iParent, pSub->pEList); + } + if( pSub->pWhere ){ + pWhere = sqlite3ExprDup(db, pSub->pWhere, 0); + }else{ + pWhere = 0; + } + if( subqueryIsAgg ){ + assert( pParent->pHaving==0 ); + pParent->pHaving = pParent->pWhere; + pParent->pWhere = pWhere; + pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList); + pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving, + sqlite3ExprDup(db, pSub->pHaving, 0)); + assert( pParent->pGroupBy==0 ); + pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0); + }else{ + pParent->pWhere = substExpr(db, pParent->pWhere, iParent, pSub->pEList); + pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere); + } + + /* The flattened query is distinct if either the inner or the + ** outer query is distinct. + */ + pParent->selFlags |= pSub->selFlags & SF_Distinct; + + /* + ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y; + ** + ** One is tempted to try to add a and b to combine the limits. But this + ** does not work if either limit is negative. + */ + if( pSub->pLimit ){ + pParent->pLimit = pSub->pLimit; + pSub->pLimit = 0; + } + } + + /* Finially, delete what is left of the subquery and return + ** success. + */ + sqlite3SelectDelete(db, pSub1); + + return 1; +} +#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ + +/* +** Analyze the SELECT statement passed as an argument to see if it +** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if +** it is, or 0 otherwise. At present, a query is considered to be +** a min()/max() query if: +** +** 1. There is a single object in the FROM clause. +** +** 2. There is a single expression in the result set, and it is +** either min(x) or max(x), where x is a column reference. +*/ +static u8 minMaxQuery(Select *p){ + Expr *pExpr; + ExprList *pEList = p->pEList; + + if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL; + pExpr = pEList->a[0].pExpr; + if( pExpr->op!=TK_AGG_FUNCTION ) return 0; + if( NEVER(ExprHasProperty(pExpr, EP_xIsSelect)) ) return 0; + pEList = pExpr->x.pList; + if( pEList==0 || pEList->nExpr!=1 ) return 0; + if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL; + assert( !ExprHasProperty(pExpr, EP_IntValue) ); + if( sqlite3StrICmp(pExpr->u.zToken,"min")==0 ){ + return WHERE_ORDERBY_MIN; + }else if( sqlite3StrICmp(pExpr->u.zToken,"max")==0 ){ + return WHERE_ORDERBY_MAX; + } + return WHERE_ORDERBY_NORMAL; +} + +/* +** The select statement passed as the first argument is an aggregate query. +** The second argment is the associated aggregate-info object. This +** function tests if the SELECT is of the form: +** +** SELECT count(*) FROM <tbl> +** +** where table is a database table, not a sub-select or view. If the query +** does match this pattern, then a pointer to the Table object representing +** <tbl> is returned. Otherwise, 0 is returned. +*/ +static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){ + Table *pTab; + Expr *pExpr; + + assert( !p->pGroupBy ); + + if( p->pWhere || p->pEList->nExpr!=1 + || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect + ){ + return 0; + } + pTab = p->pSrc->a[0].pTab; + pExpr = p->pEList->a[0].pExpr; + assert( pTab && !pTab->pSelect && pExpr ); + + if( IsVirtual(pTab) ) return 0; + if( pExpr->op!=TK_AGG_FUNCTION ) return 0; + if( (pAggInfo->aFunc[0].pFunc->flags&SQLITE_FUNC_COUNT)==0 ) return 0; + if( pExpr->flags&EP_Distinct ) return 0; + + return pTab; +} + +/* +** If the source-list item passed as an argument was augmented with an +** INDEXED BY clause, then try to locate the specified index. If there +** was such a clause and the named index cannot be found, return +** SQLITE_ERROR and leave an error in pParse. Otherwise, populate +** pFrom->pIndex and return SQLITE_OK. +*/ +int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){ + if( pFrom->pTab && pFrom->zIndex ){ + Table *pTab = pFrom->pTab; + char *zIndex = pFrom->zIndex; + Index *pIdx; + for(pIdx=pTab->pIndex; + pIdx && sqlite3StrICmp(pIdx->zName, zIndex); + pIdx=pIdx->pNext + ); + if( !pIdx ){ + sqlite3ErrorMsg(pParse, "no such index: %s", zIndex, 0); + pParse->checkSchema = 1; + return SQLITE_ERROR; + } + pFrom->pIndex = pIdx; + } + return SQLITE_OK; +} + +/* +** This routine is a Walker callback for "expanding" a SELECT statement. +** "Expanding" means to do the following: +** +** (1) Make sure VDBE cursor numbers have been assigned to every +** element of the FROM clause. +** +** (2) Fill in the pTabList->a[].pTab fields in the SrcList that +** defines FROM clause. When views appear in the FROM clause, +** fill pTabList->a[].pSelect with a copy of the SELECT statement +** that implements the view. A copy is made of the view's SELECT +** statement so that we can freely modify or delete that statement +** without worrying about messing up the presistent representation +** of the view. +** +** (3) Add terms to the WHERE clause to accomodate the NATURAL keyword +** on joins and the ON and USING clause of joins. +** +** (4) Scan the list of columns in the result set (pEList) looking +** for instances of the "*" operator or the TABLE.* operator. +** If found, expand each "*" to be every column in every table +** and TABLE.* to be every column in TABLE. +** +*/ +static int selectExpander(Walker *pWalker, Select *p){ + Parse *pParse = pWalker->pParse; + int i, j, k; + SrcList *pTabList; + ExprList *pEList; + struct SrcList_item *pFrom; + sqlite3 *db = pParse->db; + + if( db->mallocFailed ){ + return WRC_Abort; + } + if( NEVER(p->pSrc==0) || (p->selFlags & SF_Expanded)!=0 ){ + return WRC_Prune; + } + p->selFlags |= SF_Expanded; + pTabList = p->pSrc; + pEList = p->pEList; + + /* Make sure cursor numbers have been assigned to all entries in + ** the FROM clause of the SELECT statement. + */ + sqlite3SrcListAssignCursors(pParse, pTabList); + + /* Look up every table named in the FROM clause of the select. If + ** an entry of the FROM clause is a subquery instead of a table or view, + ** then create a transient table structure to describe the subquery. + */ + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ + Table *pTab; + if( pFrom->pTab!=0 ){ + /* This statement has already been prepared. There is no need + ** to go further. */ + assert( i==0 ); + return WRC_Prune; + } + if( pFrom->zName==0 ){ +#ifndef SQLITE_OMIT_SUBQUERY + Select *pSel = pFrom->pSelect; + /* A sub-query in the FROM clause of a SELECT */ + assert( pSel!=0 ); + assert( pFrom->pTab==0 ); + sqlite3WalkSelect(pWalker, pSel); + pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); + if( pTab==0 ) return WRC_Abort; + pTab->nRef = 1; + pTab->zName = sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pTab); + while( pSel->pPrior ){ pSel = pSel->pPrior; } + selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol); + pTab->iPKey = -1; + pTab->nRowEst = 1000000; + pTab->tabFlags |= TF_Ephemeral; +#endif + }else{ + /* An ordinary table or view name in the FROM clause */ + assert( pFrom->pTab==0 ); + pFrom->pTab = pTab = + sqlite3LocateTable(pParse,0,pFrom->zName,pFrom->zDatabase); + if( pTab==0 ) return WRC_Abort; + pTab->nRef++; +#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE) + if( pTab->pSelect || IsVirtual(pTab) ){ + /* We reach here if the named table is a really a view */ + if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort; + assert( pFrom->pSelect==0 ); + pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0); + sqlite3WalkSelect(pWalker, pFrom->pSelect); + } +#endif + } + + /* Locate the index named by the INDEXED BY clause, if any. */ + if( sqlite3IndexedByLookup(pParse, pFrom) ){ + return WRC_Abort; + } + } + + /* Process NATURAL keywords, and ON and USING clauses of joins. + */ + if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){ + return WRC_Abort; + } + + /* For every "*" that occurs in the column list, insert the names of + ** all columns in all tables. And for every TABLE.* insert the names + ** of all columns in TABLE. The parser inserted a special expression + ** with the TK_ALL operator for each "*" that it found in the column list. + ** The following code just has to locate the TK_ALL expressions and expand + ** each one to the list of all columns in all tables. + ** + ** The first loop just checks to see if there are any "*" operators + ** that need expanding. + */ + for(k=0; k<pEList->nExpr; k++){ + Expr *pE = pEList->a[k].pExpr; + if( pE->op==TK_ALL ) break; + assert( pE->op!=TK_DOT || pE->pRight!=0 ); + assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) ); + if( pE->op==TK_DOT && pE->pRight->op==TK_ALL ) break; + } + if( k<pEList->nExpr ){ + /* + ** If we get here it means the result set contains one or more "*" + ** operators that need to be expanded. Loop through each expression + ** in the result set and expand them one by one. + */ + struct ExprList_item *a = pEList->a; + ExprList *pNew = 0; + int flags = pParse->db->flags; + int longNames = (flags & SQLITE_FullColNames)!=0 + && (flags & SQLITE_ShortColNames)==0; + + for(k=0; k<pEList->nExpr; k++){ + Expr *pE = a[k].pExpr; + assert( pE->op!=TK_DOT || pE->pRight!=0 ); + if( pE->op!=TK_ALL && (pE->op!=TK_DOT || pE->pRight->op!=TK_ALL) ){ + /* This particular expression does not need to be expanded. + */ + pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr); + if( pNew ){ + pNew->a[pNew->nExpr-1].zName = a[k].zName; + pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan; + a[k].zName = 0; + a[k].zSpan = 0; + } + a[k].pExpr = 0; + }else{ + /* This expression is a "*" or a "TABLE.*" and needs to be + ** expanded. */ + int tableSeen = 0; /* Set to 1 when TABLE matches */ + char *zTName; /* text of name of TABLE */ + if( pE->op==TK_DOT ){ + assert( pE->pLeft!=0 ); + assert( !ExprHasProperty(pE->pLeft, EP_IntValue) ); + zTName = pE->pLeft->u.zToken; + }else{ + zTName = 0; + } + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ + Table *pTab = pFrom->pTab; + char *zTabName = pFrom->zAlias; + if( zTabName==0 ){ + zTabName = pTab->zName; + } + if( db->mallocFailed ) break; + if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){ + continue; + } + tableSeen = 1; + for(j=0; j<pTab->nCol; j++){ + Expr *pExpr, *pRight; + char *zName = pTab->aCol[j].zName; + char *zColname; /* The computed column name */ + char *zToFree; /* Malloced string that needs to be freed */ + Token sColname; /* Computed column name as a token */ + + /* If a column is marked as 'hidden' (currently only possible + ** for virtual tables), do not include it in the expanded + ** result-set list. + */ + if( IsHiddenColumn(&pTab->aCol[j]) ){ + assert(IsVirtual(pTab)); + continue; + } + + if( i>0 && zTName==0 ){ + if( (pFrom->jointype & JT_NATURAL)!=0 + && tableAndColumnIndex(pTabList, i, zName, 0, 0) + ){ + /* In a NATURAL join, omit the join columns from the + ** table to the right of the join */ + continue; + } + if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){ + /* In a join with a USING clause, omit columns in the + ** using clause from the table on the right. */ + continue; + } + } + pRight = sqlite3Expr(db, TK_ID, zName); + zColname = zName; + zToFree = 0; + if( longNames || pTabList->nSrc>1 ){ + Expr *pLeft; + pLeft = sqlite3Expr(db, TK_ID, zTabName); + pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0); + if( longNames ){ + zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName); + zToFree = zColname; + } + }else{ + pExpr = pRight; + } + pNew = sqlite3ExprListAppend(pParse, pNew, pExpr); + sColname.z = zColname; + sColname.n = sqlite3Strlen30(zColname); + sqlite3ExprListSetName(pParse, pNew, &sColname, 0); + sqlite3DbFree(db, zToFree); + } + } + if( !tableSeen ){ + if( zTName ){ + sqlite3ErrorMsg(pParse, "no such table: %s", zTName); + }else{ + sqlite3ErrorMsg(pParse, "no tables specified"); + } + } + } + } + sqlite3ExprListDelete(db, pEList); + p->pEList = pNew; + } +#if SQLITE_MAX_COLUMN + if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){ + sqlite3ErrorMsg(pParse, "too many columns in result set"); + } +#endif + return WRC_Continue; +} + +/* +** No-op routine for the parse-tree walker. +** +** When this routine is the Walker.xExprCallback then expression trees +** are walked without any actions being taken at each node. Presumably, +** when this routine is used for Walker.xExprCallback then +** Walker.xSelectCallback is set to do something useful for every +** subquery in the parser tree. +*/ +static int exprWalkNoop(Walker *NotUsed, Expr *NotUsed2){ + UNUSED_PARAMETER2(NotUsed, NotUsed2); + return WRC_Continue; +} + +/* +** This routine "expands" a SELECT statement and all of its subqueries. +** For additional information on what it means to "expand" a SELECT +** statement, see the comment on the selectExpand worker callback above. +** +** Expanding a SELECT statement is the first step in processing a +** SELECT statement. The SELECT statement must be expanded before +** name resolution is performed. +** +** If anything goes wrong, an error message is written into pParse. +** The calling function can detect the problem by looking at pParse->nErr +** and/or pParse->db->mallocFailed. +*/ +static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){ + Walker w; + w.xSelectCallback = selectExpander; + w.xExprCallback = exprWalkNoop; + w.pParse = pParse; + sqlite3WalkSelect(&w, pSelect); +} + + +#ifndef SQLITE_OMIT_SUBQUERY +/* +** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo() +** interface. +** +** For each FROM-clause subquery, add Column.zType and Column.zColl +** information to the Table structure that represents the result set +** of that subquery. +** +** The Table structure that represents the result set was constructed +** by selectExpander() but the type and collation information was omitted +** at that point because identifiers had not yet been resolved. This +** routine is called after identifier resolution. +*/ +static int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){ + Parse *pParse; + int i; + SrcList *pTabList; + struct SrcList_item *pFrom; + + assert( p->selFlags & SF_Resolved ); + if( (p->selFlags & SF_HasTypeInfo)==0 ){ + p->selFlags |= SF_HasTypeInfo; + pParse = pWalker->pParse; + pTabList = p->pSrc; + for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ + Table *pTab = pFrom->pTab; + if( ALWAYS(pTab!=0) && (pTab->tabFlags & TF_Ephemeral)!=0 ){ + /* A sub-query in the FROM clause of a SELECT */ + Select *pSel = pFrom->pSelect; + assert( pSel ); + while( pSel->pPrior ) pSel = pSel->pPrior; + selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSel); + } + } + } + return WRC_Continue; +} +#endif + + +/* +** This routine adds datatype and collating sequence information to +** the Table structures of all FROM-clause subqueries in a +** SELECT statement. +** +** Use this routine after name resolution. +*/ +static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){ +#ifndef SQLITE_OMIT_SUBQUERY + Walker w; + w.xSelectCallback = selectAddSubqueryTypeInfo; + w.xExprCallback = exprWalkNoop; + w.pParse = pParse; + sqlite3WalkSelect(&w, pSelect); +#endif +} + + +/* +** This routine sets of a SELECT statement for processing. The +** following is accomplished: +** +** * VDBE Cursor numbers are assigned to all FROM-clause terms. +** * Ephemeral Table objects are created for all FROM-clause subqueries. +** * ON and USING clauses are shifted into WHERE statements +** * Wildcards "*" and "TABLE.*" in result sets are expanded. +** * Identifiers in expression are matched to tables. +** +** This routine acts recursively on all subqueries within the SELECT. +*/ +void sqlite3SelectPrep( + Parse *pParse, /* The parser context */ + Select *p, /* The SELECT statement being coded. */ + NameContext *pOuterNC /* Name context for container */ +){ + sqlite3 *db; + if( NEVER(p==0) ) return; + db = pParse->db; + if( p->selFlags & SF_HasTypeInfo ) return; + sqlite3SelectExpand(pParse, p); + if( pParse->nErr || db->mallocFailed ) return; + sqlite3ResolveSelectNames(pParse, p, pOuterNC); + if( pParse->nErr || db->mallocFailed ) return; + sqlite3SelectAddTypeInfo(pParse, p); +} + +/* +** Reset the aggregate accumulator. +** +** The aggregate accumulator is a set of memory cells that hold +** intermediate results while calculating an aggregate. This +** routine simply stores NULLs in all of those memory cells. +*/ +static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){ + Vdbe *v = pParse->pVdbe; + int i; + struct AggInfo_func *pFunc; + if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){ + return; + } + for(i=0; i<pAggInfo->nColumn; i++){ + sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem); + } + for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){ + sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem); + if( pFunc->iDistinct>=0 ){ + Expr *pE = pFunc->pExpr; + assert( !ExprHasProperty(pE, EP_xIsSelect) ); + if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){ + sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one " + "argument"); + pFunc->iDistinct = -1; + }else{ + KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList); + sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0, + (char*)pKeyInfo, P4_KEYINFO_HANDOFF); + } + } + } +} + +/* +** Invoke the OP_AggFinalize opcode for every aggregate function +** in the AggInfo structure. +*/ +static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){ + Vdbe *v = pParse->pVdbe; + int i; + struct AggInfo_func *pF; + for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){ + ExprList *pList = pF->pExpr->x.pList; + assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); + sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0, + (void*)pF->pFunc, P4_FUNCDEF); + } +} + +/* +** Update the accumulator memory cells for an aggregate based on +** the current cursor position. +*/ +static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){ + Vdbe *v = pParse->pVdbe; + int i; + struct AggInfo_func *pF; + struct AggInfo_col *pC; + + pAggInfo->directMode = 1; + sqlite3ExprCacheClear(pParse); + for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){ + int nArg; + int addrNext = 0; + int regAgg; + ExprList *pList = pF->pExpr->x.pList; + assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); + if( pList ){ + nArg = pList->nExpr; + regAgg = sqlite3GetTempRange(pParse, nArg); + sqlite3ExprCodeExprList(pParse, pList, regAgg, 1); + }else{ + nArg = 0; + regAgg = 0; + } + if( pF->iDistinct>=0 ){ + addrNext = sqlite3VdbeMakeLabel(v); + assert( nArg==1 ); + codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg); + } + if( pF->pFunc->flags & SQLITE_FUNC_NEEDCOLL ){ + CollSeq *pColl = 0; + struct ExprList_item *pItem; + int j; + assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */ + for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){ + pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr); + } + if( !pColl ){ + pColl = pParse->db->pDfltColl; + } + sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ); + } + sqlite3VdbeAddOp4(v, OP_AggStep, 0, regAgg, pF->iMem, + (void*)pF->pFunc, P4_FUNCDEF); + sqlite3VdbeChangeP5(v, (u8)nArg); + sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg); + sqlite3ReleaseTempRange(pParse, regAgg, nArg); + if( addrNext ){ + sqlite3VdbeResolveLabel(v, addrNext); + sqlite3ExprCacheClear(pParse); + } + } + + /* Before populating the accumulator registers, clear the column cache. + ** Otherwise, if any of the required column values are already present + ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value + ** to pC->iMem. But by the time the value is used, the original register + ** may have been used, invalidating the underlying buffer holding the + ** text or blob value. See ticket [883034dcb5]. + ** + ** Another solution would be to change the OP_SCopy used to copy cached + ** values to an OP_Copy. + */ + sqlite3ExprCacheClear(pParse); + for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){ + sqlite3ExprCode(pParse, pC->pExpr, pC->iMem); + } + pAggInfo->directMode = 0; + sqlite3ExprCacheClear(pParse); +} + +/* +** Add a single OP_Explain instruction to the VDBE to explain a simple +** count(*) query ("SELECT count(*) FROM pTab"). +*/ +#ifndef SQLITE_OMIT_EXPLAIN +static void explainSimpleCount( + Parse *pParse, /* Parse context */ + Table *pTab, /* Table being queried */ + Index *pIdx /* Index used to optimize scan, or NULL */ +){ + if( pParse->explain==2 ){ + char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s %s%s(~%d rows)", + pTab->zName, + pIdx ? "USING COVERING INDEX " : "", + pIdx ? pIdx->zName : "", + pTab->nRowEst + ); + sqlite3VdbeAddOp4( + pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC + ); + } +} +#else +# define explainSimpleCount(a,b,c) +#endif + +/* +** Generate code for the SELECT statement given in the p argument. +** +** The results are distributed in various ways depending on the +** contents of the SelectDest structure pointed to by argument pDest +** as follows: +** +** pDest->eDest Result +** ------------ ------------------------------------------- +** SRT_Output Generate a row of output (using the OP_ResultRow +** opcode) for each row in the result set. +** +** SRT_Mem Only valid if the result is a single column. +** Store the first column of the first result row +** in register pDest->iParm then abandon the rest +** of the query. This destination implies "LIMIT 1". +** +** SRT_Set The result must be a single column. Store each +** row of result as the key in table pDest->iParm. +** Apply the affinity pDest->affinity before storing +** results. Used to implement "IN (SELECT ...)". +** +** SRT_Union Store results as a key in a temporary table pDest->iParm. +** +** SRT_Except Remove results from the temporary table pDest->iParm. +** +** SRT_Table Store results in temporary table pDest->iParm. +** This is like SRT_EphemTab except that the table +** is assumed to already be open. +** +** SRT_EphemTab Create an temporary table pDest->iParm and store +** the result there. The cursor is left open after +** returning. This is like SRT_Table except that +** this destination uses OP_OpenEphemeral to create +** the table first. +** +** SRT_Coroutine Generate a co-routine that returns a new row of +** results each time it is invoked. The entry point +** of the co-routine is stored in register pDest->iParm. +** +** SRT_Exists Store a 1 in memory cell pDest->iParm if the result +** set is not empty. +** +** SRT_Discard Throw the results away. This is used by SELECT +** statements within triggers whose only purpose is +** the side-effects of functions. +** +** This routine returns the number of errors. If any errors are +** encountered, then an appropriate error message is left in +** pParse->zErrMsg. +** +** This routine does NOT free the Select structure passed in. The +** calling function needs to do that. +*/ +int sqlite3Select( + Parse *pParse, /* The parser context */ + Select *p, /* The SELECT statement being coded. */ + SelectDest *pDest /* What to do with the query results */ +){ + int i, j; /* Loop counters */ + WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */ + Vdbe *v; /* The virtual machine under construction */ + int isAgg; /* True for select lists like "count(*)" */ + ExprList *pEList; /* List of columns to extract. */ + SrcList *pTabList; /* List of tables to select from */ + Expr *pWhere; /* The WHERE clause. May be NULL */ + ExprList *pOrderBy; /* The ORDER BY clause. May be NULL */ + ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */ + Expr *pHaving; /* The HAVING clause. May be NULL */ + int isDistinct; /* True if the DISTINCT keyword is present */ + int distinct; /* Table to use for the distinct set */ + int rc = 1; /* Value to return from this function */ + int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */ + int addrDistinctIndex; /* Address of an OP_OpenEphemeral instruction */ + AggInfo sAggInfo; /* Information used by aggregate queries */ + int iEnd; /* Address of the end of the query */ + sqlite3 *db; /* The database connection */ + +#ifndef SQLITE_OMIT_EXPLAIN + int iRestoreSelectId = pParse->iSelectId; + pParse->iSelectId = pParse->iNextSelectId++; +#endif + + db = pParse->db; + if( p==0 || db->mallocFailed || pParse->nErr ){ + return 1; + } + if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1; + memset(&sAggInfo, 0, sizeof(sAggInfo)); + + if( IgnorableOrderby(pDest) ){ + assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || + pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard); + /* If ORDER BY makes no difference in the output then neither does + ** DISTINCT so it can be removed too. */ + sqlite3ExprListDelete(db, p->pOrderBy); + p->pOrderBy = 0; + p->selFlags &= ~SF_Distinct; + } + sqlite3SelectPrep(pParse, p, 0); + pOrderBy = p->pOrderBy; + pTabList = p->pSrc; + pEList = p->pEList; + if( pParse->nErr || db->mallocFailed ){ + goto select_end; + } + isAgg = (p->selFlags & SF_Aggregate)!=0; + assert( pEList!=0 ); + + /* Begin generating code. + */ + v = sqlite3GetVdbe(pParse); + if( v==0 ) goto select_end; + + /* If writing to memory or generating a set + ** only a single column may be output. + */ +#ifndef SQLITE_OMIT_SUBQUERY + if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){ + goto select_end; + } +#endif + + /* Generate code for all sub-queries in the FROM clause + */ +#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) + for(i=0; !p->pPrior && i<pTabList->nSrc; i++){ + struct SrcList_item *pItem = &pTabList->a[i]; + SelectDest dest; + Select *pSub = pItem->pSelect; + int isAggSub; + + if( pSub==0 ) continue; + if( pItem->addrFillSub ){ + sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub); + continue; + } + + /* Increment Parse.nHeight by the height of the largest expression + ** tree refered to by this, the parent select. The child select + ** may contain expression trees of at most + ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit + ** more conservative than necessary, but much easier than enforcing + ** an exact limit. + */ + pParse->nHeight += sqlite3SelectExprHeight(p); + + isAggSub = (pSub->selFlags & SF_Aggregate)!=0; + if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){ + /* This subquery can be absorbed into its parent. */ + if( isAggSub ){ + isAgg = 1; + p->selFlags |= SF_Aggregate; + } + i = -1; + }else{ + /* Generate a subroutine that will fill an ephemeral table with + ** the content of this subquery. pItem->addrFillSub will point + ** to the address of the generated subroutine. pItem->regReturn + ** is a register allocated to hold the subroutine return address + */ + int topAddr; + int onceAddr = 0; + int retAddr; + assert( pItem->addrFillSub==0 ); + pItem->regReturn = ++pParse->nMem; + topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn); + pItem->addrFillSub = topAddr+1; + VdbeNoopComment((v, "materialize %s", pItem->pTab->zName)); + if( pItem->isCorrelated==0 && pParse->pTriggerTab==0 ){ + /* If the subquery is no correlated and if we are not inside of + ** a trigger, then we only need to compute the value of the subquery + ** once. */ + int regOnce = ++pParse->nMem; + onceAddr = sqlite3VdbeAddOp1(v, OP_Once, regOnce); + } + sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor); + explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); + sqlite3Select(pParse, pSub, &dest); + pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow; + if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr); + retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn); + VdbeComment((v, "end %s", pItem->pTab->zName)); + sqlite3VdbeChangeP1(v, topAddr, retAddr); + + } + if( /*pParse->nErr ||*/ db->mallocFailed ){ + goto select_end; + } + pParse->nHeight -= sqlite3SelectExprHeight(p); + pTabList = p->pSrc; + if( !IgnorableOrderby(pDest) ){ + pOrderBy = p->pOrderBy; + } + } + pEList = p->pEList; +#endif + pWhere = p->pWhere; + pGroupBy = p->pGroupBy; + pHaving = p->pHaving; + isDistinct = (p->selFlags & SF_Distinct)!=0; + +#ifndef SQLITE_OMIT_COMPOUND_SELECT + /* If there is are a sequence of queries, do the earlier ones first. + */ + if( p->pPrior ){ + if( p->pRightmost==0 ){ + Select *pLoop, *pRight = 0; + int cnt = 0; + int mxSelect; + for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){ + pLoop->pRightmost = p; + pLoop->pNext = pRight; + pRight = pLoop; + } + mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT]; + if( mxSelect && cnt>mxSelect ){ + sqlite3ErrorMsg(pParse, "too many terms in compound SELECT"); + goto select_end; + } + } + rc = multiSelect(pParse, p, pDest); + explainSetInteger(pParse->iSelectId, iRestoreSelectId); + return rc; + } +#endif + + /* If there is both a GROUP BY and an ORDER BY clause and they are + ** identical, then disable the ORDER BY clause since the GROUP BY + ** will cause elements to come out in the correct order. This is + ** an optimization - the correct answer should result regardless. + ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER + ** to disable this optimization for testing purposes. + */ + if( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0 + && (db->flags & SQLITE_GroupByOrder)==0 ){ + pOrderBy = 0; + } + + /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and + ** if the select-list is the same as the ORDER BY list, then this query + ** can be rewritten as a GROUP BY. In other words, this: + ** + ** SELECT DISTINCT xyz FROM ... ORDER BY xyz + ** + ** is transformed to: + ** + ** SELECT xyz FROM ... GROUP BY xyz + ** + ** The second form is preferred as a single index (or temp-table) may be + ** used for both the ORDER BY and DISTINCT processing. As originally + ** written the query must use a temp-table for at least one of the ORDER + ** BY and DISTINCT, and an index or separate temp-table for the other. + */ + if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct + && sqlite3ExprListCompare(pOrderBy, p->pEList)==0 + ){ + p->selFlags &= ~SF_Distinct; + p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0); + pGroupBy = p->pGroupBy; + pOrderBy = 0; + } + + /* If there is an ORDER BY clause, then this sorting + ** index might end up being unused if the data can be + ** extracted in pre-sorted order. If that is the case, then the + ** OP_OpenEphemeral instruction will be changed to an OP_Noop once + ** we figure out that the sorting index is not needed. The addrSortIndex + ** variable is used to facilitate that change. + */ + if( pOrderBy ){ + KeyInfo *pKeyInfo; + pKeyInfo = keyInfoFromExprList(pParse, pOrderBy); + pOrderBy->iECursor = pParse->nTab++; + p->addrOpenEphm[2] = addrSortIndex = + sqlite3VdbeAddOp4(v, OP_OpenEphemeral, + pOrderBy->iECursor, pOrderBy->nExpr+2, 0, + (char*)pKeyInfo, P4_KEYINFO_HANDOFF); + }else{ + addrSortIndex = -1; + } + + /* If the output is destined for a temporary table, open that table. + */ + if( pDest->eDest==SRT_EphemTab ){ + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iParm, pEList->nExpr); + } + + /* Set the limiter. + */ + iEnd = sqlite3VdbeMakeLabel(v); + p->nSelectRow = (double)LARGEST_INT64; + computeLimitRegisters(pParse, p, iEnd); + if( p->iLimit==0 && addrSortIndex>=0 ){ + sqlite3VdbeGetOp(v, addrSortIndex)->opcode = OP_SorterOpen; + p->selFlags |= SF_UseSorter; + } + + /* Open a virtual index to use for the distinct set. + */ + if( p->selFlags & SF_Distinct ){ + KeyInfo *pKeyInfo; + distinct = pParse->nTab++; + pKeyInfo = keyInfoFromExprList(pParse, p->pEList); + addrDistinctIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0, + (char*)pKeyInfo, P4_KEYINFO_HANDOFF); + sqlite3VdbeChangeP5(v, BTREE_UNORDERED); + }else{ + distinct = addrDistinctIndex = -1; + } + + /* Aggregate and non-aggregate queries are handled differently */ + if( !isAgg && pGroupBy==0 ){ + ExprList *pDist = (isDistinct ? p->pEList : 0); + + /* Begin the database scan. */ + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, pDist, 0); + if( pWInfo==0 ) goto select_end; + if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut; + + /* If sorting index that was created by a prior OP_OpenEphemeral + ** instruction ended up not being needed, then change the OP_OpenEphemeral + ** into an OP_Noop. + */ + if( addrSortIndex>=0 && pOrderBy==0 ){ + sqlite3VdbeChangeToNoop(v, addrSortIndex); + p->addrOpenEphm[2] = -1; + } + + if( pWInfo->eDistinct ){ + VdbeOp *pOp; /* No longer required OpenEphemeral instr. */ + + assert( addrDistinctIndex>=0 ); + pOp = sqlite3VdbeGetOp(v, addrDistinctIndex); + + assert( isDistinct ); + assert( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED + || pWInfo->eDistinct==WHERE_DISTINCT_UNIQUE + ); + distinct = -1; + if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED ){ + int iJump; + int iExpr; + int iFlag = ++pParse->nMem; + int iBase = pParse->nMem+1; + int iBase2 = iBase + pEList->nExpr; + pParse->nMem += (pEList->nExpr*2); + + /* Change the OP_OpenEphemeral coded earlier to an OP_Integer. The + ** OP_Integer initializes the "first row" flag. */ + pOp->opcode = OP_Integer; + pOp->p1 = 1; + pOp->p2 = iFlag; + + sqlite3ExprCodeExprList(pParse, pEList, iBase, 1); + iJump = sqlite3VdbeCurrentAddr(v) + 1 + pEList->nExpr + 1 + 1; + sqlite3VdbeAddOp2(v, OP_If, iFlag, iJump-1); + for(iExpr=0; iExpr<pEList->nExpr; iExpr++){ + CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[iExpr].pExpr); + sqlite3VdbeAddOp3(v, OP_Ne, iBase+iExpr, iJump, iBase2+iExpr); + sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ); + sqlite3VdbeChangeP5(v, SQLITE_NULLEQ); + } + sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iContinue); + + sqlite3VdbeAddOp2(v, OP_Integer, 0, iFlag); + assert( sqlite3VdbeCurrentAddr(v)==iJump ); + sqlite3VdbeAddOp3(v, OP_Move, iBase, iBase2, pEList->nExpr); + }else{ + pOp->opcode = OP_Noop; + } + } + + /* Use the standard inner loop. */ + selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, pDest, + pWInfo->iContinue, pWInfo->iBreak); + + /* End the database scan loop. + */ + sqlite3WhereEnd(pWInfo); + }else{ + /* This is the processing for aggregate queries */ + NameContext sNC; /* Name context for processing aggregate information */ + int iAMem; /* First Mem address for storing current GROUP BY */ + int iBMem; /* First Mem address for previous GROUP BY */ + int iUseFlag; /* Mem address holding flag indicating that at least + ** one row of the input to the aggregator has been + ** processed */ + int iAbortFlag; /* Mem address which causes query abort if positive */ + int groupBySort; /* Rows come from source in GROUP BY order */ + int addrEnd; /* End of processing for this SELECT */ + int sortPTab = 0; /* Pseudotable used to decode sorting results */ + int sortOut = 0; /* Output register from the sorter */ + + /* Remove any and all aliases between the result set and the + ** GROUP BY clause. + */ + if( pGroupBy ){ + int k; /* Loop counter */ + struct ExprList_item *pItem; /* For looping over expression in a list */ + + for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){ + pItem->iAlias = 0; + } + for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){ + pItem->iAlias = 0; + } + if( p->nSelectRow>(double)100 ) p->nSelectRow = (double)100; + }else{ + p->nSelectRow = (double)1; + } + + + /* Create a label to jump to when we want to abort the query */ + addrEnd = sqlite3VdbeMakeLabel(v); + + /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in + ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the + ** SELECT statement. + */ + memset(&sNC, 0, sizeof(sNC)); + sNC.pParse = pParse; + sNC.pSrcList = pTabList; + sNC.pAggInfo = &sAggInfo; + sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0; + sAggInfo.pGroupBy = pGroupBy; + sqlite3ExprAnalyzeAggList(&sNC, pEList); + sqlite3ExprAnalyzeAggList(&sNC, pOrderBy); + if( pHaving ){ + sqlite3ExprAnalyzeAggregates(&sNC, pHaving); + } + sAggInfo.nAccumulator = sAggInfo.nColumn; + for(i=0; i<sAggInfo.nFunc; i++){ + assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) ); + sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList); + } + if( db->mallocFailed ) goto select_end; + + /* Processing for aggregates with GROUP BY is very different and + ** much more complex than aggregates without a GROUP BY. + */ + if( pGroupBy ){ + KeyInfo *pKeyInfo; /* Keying information for the group by clause */ + int j1; /* A-vs-B comparision jump */ + int addrOutputRow; /* Start of subroutine that outputs a result row */ + int regOutputRow; /* Return address register for output subroutine */ + int addrSetAbort; /* Set the abort flag and return */ + int addrTopOfLoop; /* Top of the input loop */ + int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */ + int addrReset; /* Subroutine for resetting the accumulator */ + int regReset; /* Return address register for reset subroutine */ + + /* If there is a GROUP BY clause we might need a sorting index to + ** implement it. Allocate that sorting index now. If it turns out + ** that we do not need it after all, the OP_SorterOpen instruction + ** will be converted into a Noop. + */ + sAggInfo.sortingIdx = pParse->nTab++; + pKeyInfo = keyInfoFromExprList(pParse, pGroupBy); + addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, + sAggInfo.sortingIdx, sAggInfo.nSortingColumn, + 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF); + + /* Initialize memory locations used by GROUP BY aggregate processing + */ + iUseFlag = ++pParse->nMem; + iAbortFlag = ++pParse->nMem; + regOutputRow = ++pParse->nMem; + addrOutputRow = sqlite3VdbeMakeLabel(v); + regReset = ++pParse->nMem; + addrReset = sqlite3VdbeMakeLabel(v); + iAMem = pParse->nMem + 1; + pParse->nMem += pGroupBy->nExpr; + iBMem = pParse->nMem + 1; + pParse->nMem += pGroupBy->nExpr; + sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag); + VdbeComment((v, "clear abort flag")); + sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag); + VdbeComment((v, "indicate accumulator empty")); + + /* Begin a loop that will extract all source rows in GROUP BY order. + ** This might involve two separate loops with an OP_Sort in between, or + ** it might be a single loop that uses an index to extract information + ** in the right order to begin with. + */ + sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0, 0); + if( pWInfo==0 ) goto select_end; + if( pGroupBy==0 ){ + /* The optimizer is able to deliver rows in group by order so + ** we do not have to sort. The OP_OpenEphemeral table will be + ** cancelled later because we still need to use the pKeyInfo + */ + pGroupBy = p->pGroupBy; + groupBySort = 0; + }else{ + /* Rows are coming out in undetermined order. We have to push + ** each row into a sorting index, terminate the first loop, + ** then loop over the sorting index in order to get the output + ** in sorted order + */ + int regBase; + int regRecord; + int nCol; + int nGroupBy; + + explainTempTable(pParse, + isDistinct && !(p->selFlags&SF_Distinct)?"DISTINCT":"GROUP BY"); + + groupBySort = 1; + nGroupBy = pGroupBy->nExpr; + nCol = nGroupBy + 1; + j = nGroupBy+1; + for(i=0; i<sAggInfo.nColumn; i++){ + if( sAggInfo.aCol[i].iSorterColumn>=j ){ + nCol++; + j++; + } + } + regBase = sqlite3GetTempRange(pParse, nCol); + sqlite3ExprCacheClear(pParse); + sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0); + sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx,regBase+nGroupBy); + j = nGroupBy+1; + for(i=0; i<sAggInfo.nColumn; i++){ + struct AggInfo_col *pCol = &sAggInfo.aCol[i]; + if( pCol->iSorterColumn>=j ){ + int r1 = j + regBase; + int r2; + + r2 = sqlite3ExprCodeGetColumn(pParse, + pCol->pTab, pCol->iColumn, pCol->iTable, r1); + if( r1!=r2 ){ + sqlite3VdbeAddOp2(v, OP_SCopy, r2, r1); + } + j++; + } + } + regRecord = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord); + sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord); + sqlite3ReleaseTempReg(pParse, regRecord); + sqlite3ReleaseTempRange(pParse, regBase, nCol); + sqlite3WhereEnd(pWInfo); + sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++; + sortOut = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol); + sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd); + VdbeComment((v, "GROUP BY sort")); + sAggInfo.useSortingIdx = 1; + sqlite3ExprCacheClear(pParse); + } + + /* Evaluate the current GROUP BY terms and store in b0, b1, b2... + ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth) + ** Then compare the current GROUP BY terms against the GROUP BY terms + ** from the previous row currently stored in a0, a1, a2... + */ + addrTopOfLoop = sqlite3VdbeCurrentAddr(v); + sqlite3ExprCacheClear(pParse); + if( groupBySort ){ + sqlite3VdbeAddOp2(v, OP_SorterData, sAggInfo.sortingIdx, sortOut); + } + for(j=0; j<pGroupBy->nExpr; j++){ + if( groupBySort ){ + sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j); + if( j==0 ) sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE); + }else{ + sAggInfo.directMode = 1; + sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j); + } + } + sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr, + (char*)pKeyInfo, P4_KEYINFO); + j1 = sqlite3VdbeCurrentAddr(v); + sqlite3VdbeAddOp3(v, OP_Jump, j1+1, 0, j1+1); + + /* Generate code that runs whenever the GROUP BY changes. + ** Changes in the GROUP BY are detected by the previous code + ** block. If there were no changes, this block is skipped. + ** + ** This code copies current group by terms in b0,b1,b2,... + ** over to a0,a1,a2. It then calls the output subroutine + ** and resets the aggregate accumulator registers in preparation + ** for the next GROUP BY batch. + */ + sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr); + sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); + VdbeComment((v, "output one row")); + sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); + VdbeComment((v, "check abort flag")); + sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); + VdbeComment((v, "reset accumulator")); + + /* Update the aggregate accumulators based on the content of + ** the current row + */ + sqlite3VdbeJumpHere(v, j1); + updateAccumulator(pParse, &sAggInfo); + sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag); + VdbeComment((v, "indicate data in accumulator")); + + /* End of the loop + */ + if( groupBySort ){ + sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop); + }else{ + sqlite3WhereEnd(pWInfo); + sqlite3VdbeChangeToNoop(v, addrSortingIdx); + } + + /* Output the final row of result + */ + sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); + VdbeComment((v, "output final row")); + + /* Jump over the subroutines + */ + sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEnd); + + /* Generate a subroutine that outputs a single row of the result + ** set. This subroutine first looks at the iUseFlag. If iUseFlag + ** is less than or equal to zero, the subroutine is a no-op. If + ** the processing calls for the query to abort, this subroutine + ** increments the iAbortFlag memory location before returning in + ** order to signal the caller to abort. + */ + addrSetAbort = sqlite3VdbeCurrentAddr(v); + sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag); + VdbeComment((v, "set abort flag")); + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); + sqlite3VdbeResolveLabel(v, addrOutputRow); + addrOutputRow = sqlite3VdbeCurrentAddr(v); + sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2); + VdbeComment((v, "Groupby result generator entry point")); + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); + finalizeAggFunctions(pParse, &sAggInfo); + sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL); + selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy, + distinct, pDest, + addrOutputRow+1, addrSetAbort); + sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); + VdbeComment((v, "end groupby result generator")); + + /* Generate a subroutine that will reset the group-by accumulator + */ + sqlite3VdbeResolveLabel(v, addrReset); + resetAccumulator(pParse, &sAggInfo); + sqlite3VdbeAddOp1(v, OP_Return, regReset); + + } /* endif pGroupBy. Begin aggregate queries without GROUP BY: */ + else { + ExprList *pDel = 0; +#ifndef SQLITE_OMIT_BTREECOUNT + Table *pTab; + if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){ + /* If isSimpleCount() returns a pointer to a Table structure, then + ** the SQL statement is of the form: + ** + ** SELECT count(*) FROM <tbl> + ** + ** where the Table structure returned represents table <tbl>. + ** + ** This statement is so common that it is optimized specially. The + ** OP_Count instruction is executed either on the intkey table that + ** contains the data for table <tbl> or on one of its indexes. It + ** is better to execute the op on an index, as indexes are almost + ** always spread across less pages than their corresponding tables. + */ + const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); + const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */ + Index *pIdx; /* Iterator variable */ + KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */ + Index *pBest = 0; /* Best index found so far */ + int iRoot = pTab->tnum; /* Root page of scanned b-tree */ + + sqlite3CodeVerifySchema(pParse, iDb); + sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); + + /* Search for the index that has the least amount of columns. If + ** there is such an index, and it has less columns than the table + ** does, then we can assume that it consumes less space on disk and + ** will therefore be cheaper to scan to determine the query result. + ** In this case set iRoot to the root page number of the index b-tree + ** and pKeyInfo to the KeyInfo structure required to navigate the + ** index. + ** + ** (2011-04-15) Do not do a full scan of an unordered index. + ** + ** In practice the KeyInfo structure will not be used. It is only + ** passed to keep OP_OpenRead happy. + */ + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + if( pIdx->bUnordered==0 && (!pBest || pIdx->nColumn<pBest->nColumn) ){ + pBest = pIdx; + } + } + if( pBest && pBest->nColumn<pTab->nCol ){ + iRoot = pBest->tnum; + pKeyInfo = sqlite3IndexKeyinfo(pParse, pBest); + } + + /* Open a read-only cursor, execute the OP_Count, close the cursor. */ + sqlite3VdbeAddOp3(v, OP_OpenRead, iCsr, iRoot, iDb); + if( pKeyInfo ){ + sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO_HANDOFF); + } + sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem); + sqlite3VdbeAddOp1(v, OP_Close, iCsr); + explainSimpleCount(pParse, pTab, pBest); + }else +#endif /* SQLITE_OMIT_BTREECOUNT */ + { + /* Check if the query is of one of the following forms: + ** + ** SELECT min(x) FROM ... + ** SELECT max(x) FROM ... + ** + ** If it is, then ask the code in where.c to attempt to sort results + ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause. + ** If where.c is able to produce results sorted in this order, then + ** add vdbe code to break out of the processing loop after the + ** first iteration (since the first iteration of the loop is + ** guaranteed to operate on the row with the minimum or maximum + ** value of x, the only row required). + ** + ** A special flag must be passed to sqlite3WhereBegin() to slightly + ** modify behaviour as follows: + ** + ** + If the query is a "SELECT min(x)", then the loop coded by + ** where.c should not iterate over any values with a NULL value + ** for x. + ** + ** + The optimizer code in where.c (the thing that decides which + ** index or indices to use) should place a different priority on + ** satisfying the 'ORDER BY' clause than it does in other cases. + ** Refer to code and comments in where.c for details. + */ + ExprList *pMinMax = 0; + u8 flag = minMaxQuery(p); + if( flag ){ + assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) ); + pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0); + pDel = pMinMax; + if( pMinMax && !db->mallocFailed ){ + pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; + pMinMax->a[0].pExpr->op = TK_COLUMN; + } + } + + /* This case runs if the aggregate has no GROUP BY clause. The + ** processing is much simpler since there is only a single row + ** of output. + */ + resetAccumulator(pParse, &sAggInfo); + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, 0, flag); + if( pWInfo==0 ){ + sqlite3ExprListDelete(db, pDel); + goto select_end; + } + updateAccumulator(pParse, &sAggInfo); + if( !pMinMax && flag ){ + sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak); + VdbeComment((v, "%s() by index", + (flag==WHERE_ORDERBY_MIN?"min":"max"))); + } + sqlite3WhereEnd(pWInfo); + finalizeAggFunctions(pParse, &sAggInfo); + } + + pOrderBy = 0; + sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL); + selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1, + pDest, addrEnd, addrEnd); + sqlite3ExprListDelete(db, pDel); + } + sqlite3VdbeResolveLabel(v, addrEnd); + + } /* endif aggregate query */ + + if( distinct>=0 ){ + explainTempTable(pParse, "DISTINCT"); + } + + /* If there is an ORDER BY clause, then we need to sort the results + ** and send them to the callback one by one. + */ + if( pOrderBy ){ + explainTempTable(pParse, "ORDER BY"); + generateSortTail(pParse, p, v, pEList->nExpr, pDest); + } + + /* Jump here to skip this query + */ + sqlite3VdbeResolveLabel(v, iEnd); + + /* The SELECT was successfully coded. Set the return code to 0 + ** to indicate no errors. + */ + rc = 0; + + /* Control jumps to here if an error is encountered above, or upon + ** successful coding of the SELECT. + */ +select_end: + explainSetInteger(pParse->iSelectId, iRestoreSelectId); + + /* Identify column names if results of the SELECT are to be output. + */ + if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){ + generateColumnNames(pParse, pTabList, pEList); + } + + sqlite3DbFree(db, sAggInfo.aCol); + sqlite3DbFree(db, sAggInfo.aFunc); + return rc; +} + +#if defined(SQLITE_DEBUG) +/* +******************************************************************************* +** The following code is used for testing and debugging only. The code +** that follows does not appear in normal builds. +** +** These routines are used to print out the content of all or part of a +** parse structures such as Select or Expr. Such printouts are useful +** for helping to understand what is happening inside the code generator +** during the execution of complex SELECT statements. +** +** These routine are not called anywhere from within the normal +** code base. Then are intended to be called from within the debugger +** or from temporary "printf" statements inserted for debugging. +*/ +void sqlite3PrintExpr(Expr *p){ + if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){ + sqlite3DebugPrintf("(%s", p->u.zToken); + }else{ + sqlite3DebugPrintf("(%d", p->op); + } + if( p->pLeft ){ + sqlite3DebugPrintf(" "); + sqlite3PrintExpr(p->pLeft); + } + if( p->pRight ){ + sqlite3DebugPrintf(" "); + sqlite3PrintExpr(p->pRight); + } + sqlite3DebugPrintf(")"); +} +void sqlite3PrintExprList(ExprList *pList){ + int i; + for(i=0; i<pList->nExpr; i++){ + sqlite3PrintExpr(pList->a[i].pExpr); + if( i<pList->nExpr-1 ){ + sqlite3DebugPrintf(", "); + } + } +} +void sqlite3PrintSelect(Select *p, int indent){ + sqlite3DebugPrintf("%*sSELECT(%p) ", indent, "", p); + sqlite3PrintExprList(p->pEList); + sqlite3DebugPrintf("\n"); + if( p->pSrc ){ + char *zPrefix; + int i; + zPrefix = "FROM"; + for(i=0; i<p->pSrc->nSrc; i++){ + struct SrcList_item *pItem = &p->pSrc->a[i]; + sqlite3DebugPrintf("%*s ", indent+6, zPrefix); + zPrefix = ""; + if( pItem->pSelect ){ + sqlite3DebugPrintf("(\n"); + sqlite3PrintSelect(pItem->pSelect, indent+10); + sqlite3DebugPrintf("%*s)", indent+8, ""); + }else if( pItem->zName ){ + sqlite3DebugPrintf("%s", pItem->zName); + } + if( pItem->pTab ){ + sqlite3DebugPrintf("(table: %s)", pItem->pTab->zName); + } + if( pItem->zAlias ){ + sqlite3DebugPrintf(" AS %s", pItem->zAlias); + } + if( i<p->pSrc->nSrc-1 ){ + sqlite3DebugPrintf(","); + } + sqlite3DebugPrintf("\n"); + } + } + if( p->pWhere ){ + sqlite3DebugPrintf("%*s WHERE ", indent, ""); + sqlite3PrintExpr(p->pWhere); + sqlite3DebugPrintf("\n"); + } + if( p->pGroupBy ){ + sqlite3DebugPrintf("%*s GROUP BY ", indent, ""); + sqlite3PrintExprList(p->pGroupBy); + sqlite3DebugPrintf("\n"); + } + if( p->pHaving ){ + sqlite3DebugPrintf("%*s HAVING ", indent, ""); + sqlite3PrintExpr(p->pHaving); + sqlite3DebugPrintf("\n"); + } + if( p->pOrderBy ){ + sqlite3DebugPrintf("%*s ORDER BY ", indent, ""); + sqlite3PrintExprList(p->pOrderBy); + sqlite3DebugPrintf("\n"); + } +} +/* End of the structure debug printing code +*****************************************************************************/ +#endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */ |