When vacuuming an index that uses no collations other than BINARY, assume that the order of index entries will not be changed by the VACUUM.

FossilOrigin-Name: e403460b96814ac8cb976d58b27939b3bd3c61f9

manifest

@@ -1,5 +1,5 @@
-C Reduce\sthe\sCPU\sused\sby\sCREATE\sINDEX\sstatements\sby\staking\sbetter\sadvantage\sof\sthe\sfact\sthat\skeys\sare\sinserted\sin\ssorted\sorder.
-D 2015-04-01T16:18:00.779
+C When\svacuuming\san\sindex\sthat\suses\sno\scollations\sother\sthan\sBINARY,\sassume\sthat\sthe\sorder\sof\sindex\sentries\swill\snot\sbe\schanged\sby\sthe\sVACUUM.
+D 2015-04-01T18:20:25.537
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 88a3e6261286db378fdffa1124cad11b3c05f5bb
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -190,7 +190,7 @@ F src/global.c 4f77cadbc5427d00139ba43d0f3979804cbb700e
 F src/hash.c 4263fbc955f26c2e8cdc0cf214bc42435aa4e4f5
 F src/hash.h c8f3c31722cf3277d03713909761e152a5b81094
 F src/hwtime.h d32741c8f4df852c7d959236615444e2b1063b08
-F src/insert.c 5b9243a33726008cc4132897d2be371db12a13be
+F src/insert.c 1cc9dc4e939b5dd4a74ac4a3222b89e66b074210
 F src/journal.c b4124532212b6952f42eb2c12fa3c25701d8ba8d
 F src/legacy.c ba1863ea58c4c840335a84ec276fc2b25e22bc4e
 F src/lempar.c 7274c97d24bb46631e504332ccd3bd1b37841770
@@ -235,7 +235,7 @@ F src/shell.c 3ae1e53878d2804fe77b8c8f1f6ca287a0e5d80e
 F src/sqlite.h.in 278602140d49575e8708e643161f4263e428a02a
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h 17d487c3c91b0b8c584a32fbeb393f6f795eea7d
-F src/sqliteInt.h bedf15914c09bfb5fe3ec4e3f211a4a6fc42cd33
+F src/sqliteInt.h df0ee3545220b8687d8640d433d1417b31e1675a
 F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c e7a09215315a978057fb42c640f890160dbcc45e
@@ -292,7 +292,7 @@ F src/trigger.c 25571661fdeae8c7f975ff40ffec205520a3f92f
 F src/update.c 3c4ecc282accf12d39edb8d524cf089645e55a13
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
 F src/util.c 98a7627ca48ad3265b6940915a1d08355eb3fc7e
-F src/vacuum.c 9460b9de7b2d4e34b0d374894aa6c8a0632be8ec
+F src/vacuum.c 2ddd5cad2a7b9cef7f9e431b8c7771634c6b1701
 F src/vdbe.c a9d916abb1e22355a81b0e72040917ba33c87ed7
 F src/vdbe.h 7e538ecf47dccb307ea2d087c3ddc2dd8d70e79d
 F src/vdbeInt.h 9cbaa84f53ddd2d09a0cf61a94337a3a035d08a0
@@ -1247,7 +1247,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 601e7b6b8e6bfabda03b70f75094c9014e3a3c49
-R 151febe3c42a1563a662898adadb6b2d
+P 592cdc5d7254be7032aa9c0b03405a74ca060b51
+R d93391642538d3e00eae6a1c718cf53f
 U dan
-Z 37e9d6c37bda7e19a2c8ebf1573e150d
+Z 6ea2b15ffbb091b1ac11e4173c1e9ec7

manifest.uuid

@@ -1 +1 @@
-592cdc5d7254be7032aa9c0b03405a74ca060b51
+e403460b96814ac8cb976d58b27939b3bd3c61f9

src/insert.c

@@ -1765,6 +1765,7 @@ static int xferOptimization(
   int onError,          /* How to handle constraint errors */
   int iDbDest           /* The database of pDest */
 ){
+  sqlite3 *db = pParse->db;
   ExprList *pEList;                /* The result set of the SELECT */
   Table *pSrc;                     /* The table in the FROM clause of SELECT */
   Index *pSrcIdx, *pDestIdx;       /* Source and destination indices */
@@ -1912,11 +1913,11 @@ static int xferOptimization(
   ** the extra complication to make this rule less restrictive is probably
   ** not worth the effort.  Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
   */
-  if( (pParse->db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
+  if( (db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
     return 0;
   }
 #endif
-  if( (pParse->db->flags & SQLITE_CountRows)!=0 ){
+  if( (db->flags & SQLITE_CountRows)!=0 ){
     return 0;  /* xfer opt does not play well with PRAGMA count_changes */
   }
 
@@ -1927,7 +1928,7 @@ static int xferOptimization(
 #ifdef SQLITE_TEST
   sqlite3_xferopt_count++;
 #endif
-  iDbSrc = sqlite3SchemaToIndex(pParse->db, pSrc->pSchema);
+  iDbSrc = sqlite3SchemaToIndex(db, pSrc->pSchema);
   v = sqlite3GetVdbe(pParse);
   sqlite3CodeVerifySchema(pParse, iDbSrc);
   iSrc = pParse->nTab++;
@@ -1937,14 +1938,18 @@ static int xferOptimization(
   regRowid = sqlite3GetTempReg(pParse);
   sqlite3OpenTable(pParse, iDest, iDbDest, pDest, OP_OpenWrite);
   assert( HasRowid(pDest) || destHasUniqueIdx );
-  if( (pDest->iPKey<0 && pDest->pIndex!=0)          /* (1) */
+  if( (db->flags & SQLITE_Vacuum)==0 && (
+      (pDest->iPKey<0 && pDest->pIndex!=0)          /* (1) */
    || destHasUniqueIdx                              /* (2) */
    || (onError!=OE_Abort && onError!=OE_Rollback)   /* (3) */
-  ){
+  )){
     /* In some circumstances, we are able to run the xfer optimization
-    ** only if the destination table is initially empty.  This code makes
-    ** that determination.  Conditions under which the destination must
-    ** be empty:
+    ** only if the destination table is initially empty. Unless the
+    ** SQLITE_Vacuum flag is set, this block generates code to make
+    ** that determination. If SQLITE_Vacuum is set, then the destination
+    ** table is always empty.
+    **
+    ** Conditions under which the destination must be empty:
     **
     ** (1) There is no INTEGER PRIMARY KEY but there are indices.
     **     (If the destination is not initially empty, the rowid fields
@@ -1987,6 +1992,7 @@ static int xferOptimization(
     sqlite3TableLock(pParse, iDbSrc, pSrc->tnum, 0, pSrc->zName);
   }
   for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
+    u8 useSeekResult = 0;
     for(pSrcIdx=pSrc->pIndex; ALWAYS(pSrcIdx); pSrcIdx=pSrcIdx->pNext){
       if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
     }
@@ -2000,7 +2006,33 @@ static int xferOptimization(
     VdbeComment((v, "%s", pDestIdx->zName));
     addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0); VdbeCoverage(v);
     sqlite3VdbeAddOp2(v, OP_RowKey, iSrc, regData);
+    if( db->flags & SQLITE_Vacuum ){
+      /* This INSERT command is part of a VACUUM operation, which guarantees
+      ** that the destination table is empty. If all indexed columns use
+      ** collation sequence BINARY, then it can also be assumed that the
+      ** index will be populated by inserting keys in strictly sorted 
+      ** order. In this case, instead of seeking within the b-tree as part
+      ** of every OP_IdxInsert opcode, an OP_Last is added before the
+      ** OP_IdxInsert to seek to the point within the b-tree where each key 
+      ** should be inserted. This is faster.
+      **
+      ** If any of the indexed columns use a collation sequence other than
+      ** BINARY, this optimization is disabled. This is because the user 
+      ** might change the definition of a collation sequence and then run
+      ** a VACUUM command. In that case keys may not be written in strictly
+      ** sorted order.  */
+      int i;
+      for(i=0; i<pSrcIdx->nColumn; i++){
+        char *zColl = pSrcIdx->azColl[i];
+        if( zColl && sqlite3_stricmp("BINARY", zColl) ) break;
+      }
+      if( i==pSrcIdx->nColumn ){
+        useSeekResult = OPFLAG_USESEEKRESULT;
+        sqlite3VdbeAddOp3(v, OP_Last, iDest, 0, -1);
+      }
+    }
     sqlite3VdbeAddOp3(v, OP_IdxInsert, iDest, regData, 1);
+    sqlite3VdbeChangeP5(v, useSeekResult);
     sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1+1); VdbeCoverage(v);
     sqlite3VdbeJumpHere(v, addr1);
     sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);

src/sqliteInt.h

@@ -1226,6 +1226,7 @@ struct sqlite3 {
 #define SQLITE_DeferFKs       0x01000000  /* Defer all FK constraints */
 #define SQLITE_QueryOnly      0x02000000  /* Disable database changes */
 #define SQLITE_VdbeEQP        0x04000000  /* Debug EXPLAIN QUERY PLAN */
+#define SQLITE_Vacuum         0x08000000  /* Currently in a VACUUM */
 
 
 /*

src/vacuum.c

@@ -250,6 +250,8 @@ int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
   ** an "INSERT INTO vacuum_db.xxx SELECT * FROM main.xxx;" to copy
   ** the contents to the temporary database.
   */
+  assert( (db->flags & SQLITE_Vacuum)==0 );
+  db->flags |= SQLITE_Vacuum;
   rc = execExecSql(db, pzErrMsg,
       "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
       "|| ' SELECT * FROM main.' || quote(name) || ';'"
@@ -257,6 +259,8 @@ int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
       "WHERE type = 'table' AND name!='sqlite_sequence' "
       "  AND coalesce(rootpage,1)>0"
   );
+  assert( (db->flags & SQLITE_Vacuum)!=0 );
+  db->flags &= ~SQLITE_Vacuum;
   if( rc!=SQLITE_OK ) goto end_of_vacuum;
 
   /* Copy over the sequence table