From 60bc407c5fc00acc1d0608a45693b8cc61b21d79 Mon Sep 17 00:00:00 2001
From: "Damien F. Katz" <damien@apache.org>
Date: Mon, 3 Nov 2008 20:59:45 +0000
Subject: Fix for performance problem with views. Every access to a view was
 causing a disk sync, regardless if the index was updated.

git-svn-id: https://svn.apache.org/repos/asf/incubator/couchdb/trunk@710156 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_view.erl | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/couchdb/couch_view.erl b/src/couchdb/couch_view.erl
index e3623dde..4ebbb136 100644
--- a/src/couchdb/couch_view.erl
+++ b/src/couchdb/couch_view.erl
@@ -382,7 +382,7 @@ start_temp_update_loop(DbName, Fd, Lang, MapSrc, RedSrc) ->
 
 temp_update_loop(DbName, Group, NotifyPids) ->
     {ok, Db} = couch_db:open(DbName, []),
-    {ok, Group2} = update_group(Group#group{db=Db}),
+    {_Updated, Group2} = update_group(Group#group{db=Db}),
     couch_db:close(Db),
     [Pid ! {self(), {ok, Group2}} || Pid <- NotifyPids],
     garbage_collect(),
@@ -463,7 +463,10 @@ update_loop(RootDir, DbName, GroupId, #group{sig=Sig,fd=Fd}=Group, NotifyPids) -
         couch_db:close(Db)
     end,
     case Result of
-    {ok, Group2} ->
+    {same, Group2} ->
+        [Pid ! {self(), {ok, Group2}} || Pid <- NotifyPids],
+        update_loop(RootDir, DbName, GroupId, Group2, get_notify_pids(100000));
+    {updated, Group2} ->
         HeaderData = {Sig, get_index_header_data(Group2)},
         ok = couch_file:write_header(Fd, <<$r, $c, $k, 0>>, HeaderData),
         [Pid ! {self(), {ok, Group2}} || Pid <- NotifyPids],
@@ -555,9 +558,9 @@ update_group(#group{db=Db,current_seq=CurrentSeq,
     couch_query_servers:stop_doc_map(Group4#group.query_server),
     if CurrentSeq /= NewSeq ->
         {ok, Group5} = write_changes(Group4, ViewKVsToAdd2, DocIdViewIdKeys2, NewSeq),
-        {ok, Group5#group{query_server=nil}};
+        {updated, Group5#group{query_server=nil}};
     true ->
-        {ok, Group4#group{query_server=nil}}
+        {same, Group4#group{query_server=nil}}
     end.
     
 delete_index_dir(RootDir, DbName) ->
-- 
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