From 3fbb022b98a05d985571a188003f3dd1fb2b94a5 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Wed, 24 Sep 2014 19:47:27 +0000
Subject: [PATCH] Have each open database allocate its pTmpSpace when the first
 write cursor is opened, rather than on each insert or delete, for a small
 space savings and performance boost.

FossilOrigin-Name: 99323552c001bc9173eb2a44542234c8ef7a9845
---
 manifest      | 14 +++++++-------
 manifest.uuid |  2 +-
 src/btree.c   | 11 ++++++-----
 src/vdbe.c    |  4 ----
 4 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/manifest b/manifest
index c64e305a7f..9d16127977 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Small\sperformance\sand\ssize\soptimization\sfor\sbtreeUnlockIfUnused().
-D 2014-09-24T18:31:07.339
+C Have\seach\sopen\sdatabase\sallocate\sits\spTmpSpace\swhen\sthe\sfirst\swrite\scursor\nis\sopened,\srather\sthan\son\seach\sinsert\sor\sdelete,\sfor\sa\ssmall\sspace\ssavings\nand\sperformance\sboost.
+D 2014-09-24T19:47:27.033
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -172,7 +172,7 @@ F src/auth.c d8abcde53426275dab6243b441256fcd8ccbebb2
 F src/backup.c a31809c65623cc41849b94d368917f8bb66e6a7e
 F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb
 F src/btmutex.c 49ca66250c7dfa844a4d4cb8272b87420d27d3a5
-F src/btree.c ee77b1d3a346dd0d581e3d729524243c68ba5b96
+F src/btree.c 4d5cdfeaea4a00f796c17af246dd5b48cd525d5e
 F src/btree.h a79aa6a71e7f1055f01052b7f821bd1c2dce95c8
 F src/btreeInt.h 9db0d303b203d18871dc9a1d78a3e1ae4d62c1ef
 F src/build.c bde83dd5cf812e310a7e5ad2846790a14745bef4
@@ -289,7 +289,7 @@ F src/update.c 729f6f18fc27740591d085e1172cebe311144bf0
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
 F src/util.c 4006c01772bd8d8ac4306d523bbcee41d3e392d8
 F src/vacuum.c 59f03f92bcff57faa6a8ca256eb29ccddfb0614a
-F src/vdbe.c de1af1795bebdad20c23e82bafa2f531e9893198
+F src/vdbe.c 23db9b11f0d0a022c42bf71c2b036d32c82a9abd
 F src/vdbe.h 09f5b4e3719fa454f252322b1cdab5cf1f361327
 F src/vdbeInt.h f177bed1ec8d4eb5c7089f012aeb95f374745735
 F src/vdbeapi.c e9e33b59834e3edc8790209765e069874c269d9d
@@ -1200,7 +1200,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 1ad2bc1ed4c4ac81ac67a9660761f0eeb47c7fef
-R d6b9d6f16b042c47207345c5727aac20
+P 13c746f85d254475b10c3dd58555acd3bbead0ce
+R dd216235dc00cda1e50e4687ef88aee3
 U drh
-Z 51a889840b720ee888395fd53da3c843
+Z 5eb3b3c4f4a76619f8f4a6dc0df5e879
diff --git a/manifest.uuid b/manifest.uuid
index 838ae9d867..c31ec3cb1b 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-13c746f85d254475b10c3dd58555acd3bbead0ce
\ No newline at end of file
+99323552c001bc9173eb2a44542234c8ef7a9845
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index d8bf076e85..37aabbef77 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -3672,6 +3672,10 @@ static int btreeCursor(
   if( NEVER(wrFlag && (pBt->btsFlags & BTS_READ_ONLY)!=0) ){
     return SQLITE_READONLY;
   }
+  if( wrFlag ){
+    allocateTempSpace(pBt);
+    if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM;
+  }
   if( iTable==1 && btreePagecount(pBt)==0 ){
     assert( wrFlag==0 );
     iTable = 0;
@@ -7154,9 +7158,8 @@ int sqlite3BtreeInsert(
           pCur->pgnoRoot, nKey, nData, pPage->pgno,
           loc==0 ? "overwrite" : "new entry"));
   assert( pPage->isInit );
-  allocateTempSpace(pBt);
   newCell = pBt->pTmpSpace;
-  if( newCell==0 ) return SQLITE_NOMEM;
+  assert( newCell!=0 );
   rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
   if( rc ) goto end_insert;
   assert( szNew==cellSizePtr(pPage, newCell) );
@@ -7302,10 +7305,8 @@ int sqlite3BtreeDelete(BtCursor *pCur){
     pCell = findCell(pLeaf, pLeaf->nCell-1);
     nCell = cellSizePtr(pLeaf, pCell);
     assert( MX_CELL_SIZE(pBt) >= nCell );
-
-    allocateTempSpace(pBt);
     pTmp = pBt->pTmpSpace;
-
+    assert( pTmp!=0 );
     rc = sqlite3PagerWrite(pLeaf->pDbPage);
     insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
     dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
diff --git a/src/vdbe.c b/src/vdbe.c
index 26ca72b9f4..4c2b75f641 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3287,10 +3287,6 @@ case OP_OpenWrite: {
   assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
   sqlite3BtreeCursorHints(pCur->pCursor, (pOp->p5 & OPFLAG_BULKCSR));
 
-  /* Since it performs no memory allocation or IO, the only value that
-  ** sqlite3BtreeCursor() may return is SQLITE_OK. */
-  assert( rc==SQLITE_OK );
-
   /* Set the VdbeCursor.isTable variable. Previous versions of
   ** SQLite used to check if the root-page flags were sane at this point
   ** and report database corruption if they were not, but this check has
-- 
2.47.2