Reduce the number of VdbeRecordUnpack() calls made in vdbesort.c.

FossilOrigin-Name: 666c2c3cff51dac2ba5689b75705d99c3705673b

manifest

@@ -1,5 +1,5 @@
-C The\sbuild\sworks\sagain\swith\s-DSQLITE_OMIT_MERGE_SORT.\s\sThe\smerge-sorter\snow\navoids\sspilling\sto\sdisk\s(letting\sthe\sin-memory\slinked\slist\sgrow\swithout\nbound)\sif\sPRAGMA\stemp_store=3.
-D 2011-09-03T00:17:51.023
+C Reduce\sthe\snumber\sof\sVdbeRecordUnpack()\scalls\smade\sin\svdbesort.c.
+D 2011-09-03T14:36:13.912
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in d314143fa6be24828021d3f583ad37d9afdce505
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -245,7 +245,7 @@ F src/vdbeapi.c 11dc47987abacb76ad016dcf5abc0dc422482a98
 F src/vdbeaux.c e58acbc5ea3823922a0cd8fa21f94f39af51ee88
 F src/vdbeblob.c f024f0bf420f36b070143c32b15cc7287341ffd3
 F src/vdbemem.c 5e6effb96dd53d233361cbfaa3f0a43b9af689e9
-F src/vdbesort.c aa7ad2ef91ad7d33eb614d3fb1c4cbd068b321ad
+F src/vdbesort.c 5e38e7e1f5f6900b1b8bea49decd23c69221aed9
 F src/vdbetrace.c 5d0dc3d5fd54878cc8d6d28eb41deb8d5885b114
 F src/vtab.c 901791a47318c0562cd0c676a2c6ff1bc530e582
 F src/wal.c 3154756177d6219e233d84291d5b05f4e06ff5e9
@@ -961,7 +961,7 @@ F tool/symbols.sh caaf6ccc7300fd43353318b44524853e222557d5
 F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings.sh b7fdb2cc525f5ef4fa43c80e771636dd3690f9d2
-P a9a64592cf88580cb254fb0aac65a2f2085976ec
-R 4edd7e2341e47b4ce23f768c53615b8c
-U drh
-Z cbdc1caefa14410ba02a8248a6138d65
+P 68e26c4487696d194ee85370380e4b0e56d206ee
+R f6e37dce79fea0b74c498631cfb45ff1
+U dan
+Z cc6b7d2a23c219696518afb4690c5277

manifest.uuid

@@ -1 +1 @@
-68e26c4487696d194ee85370380e4b0e56d206ee
+666c2c3cff51dac2ba5689b75705d99c3705673b

src/vdbesort.c

@@ -303,6 +303,9 @@ static int vdbeSorterIterInit(
 ** field. For the purposes of the comparison, ignore it. Also, if bOmitRowid
 ** is true and key1 contains even a single NULL value, it is considered to
 ** be less than key2. Even if key2 also contains NULL values.
+**
+** If pKey2 is passed a NULL pointer, then it is assumed that the pCsr->aSpace
+** has been allocated and contains an unpacked record that is used as key2.
 */
 static int vdbeSorterCompare(
   VdbeCursor *pCsr,               /* Cursor object (for pKeyInfo) */
@@ -326,15 +329,20 @@ static int vdbeSorterCompare(
     pSorter->nSpace = nSpace;
   }
 
-  /* This call cannot fail. As the memory is already allocated. */
-  r2 = sqlite3VdbeRecordUnpack(pKeyInfo, nKey2, pKey2, aSpace, nSpace);
-  assert( r2 && (r2->flags & UNPACKED_NEED_FREE)==0 );
+  if( pKey2 ){
+    /* This call cannot fail. As the memory is already allocated. */
+    r2 = sqlite3VdbeRecordUnpack(pKeyInfo, nKey2, pKey2, aSpace, nSpace);
+    assert( r2 && (r2->flags & UNPACKED_NEED_FREE)==0 );
+    assert( r2==aSpace );
+  }else{
+    r2 = (UnpackedRecord *)aSpace;
+    assert( !bOmitRowid );
+  }
 
   if( bOmitRowid ){
     for(i=0; i<r2->nField-1; i++){
       if( r2->aMem[i].flags & MEM_Null ){
         *pRes = -1;
-        sqlite3VdbeDeleteUnpackedRecord(r2);
         return SQLITE_OK;
       }
     }
@@ -344,7 +352,6 @@ static int vdbeSorterCompare(
   }
 
   *pRes = sqlite3VdbeRecordCompare(nKey1, pKey1, r2);
-  /* sqlite3VdbeDeleteUnpackedRecord(r2); */
   return SQLITE_OK;
 }
 
@@ -483,6 +490,7 @@ static int vdbeSorterMerge(
   int rc = SQLITE_OK;
   SorterRecord *pFinal = 0;
   SorterRecord **pp = &pFinal;
+  int bKey2InSpace = 0;           /* True if pCsr->aSpace contains key2 */
 
   while( p1 || p2 ){
     if( p1==0 ){
@@ -493,8 +501,8 @@ static int vdbeSorterMerge(
       p1 = 0;
     }else{
       int res;
-      rc = vdbeSorterCompare(
-          pCsr, 0, p1->pVal, p1->nVal, p2->pVal, p2->nVal, &res
+      rc = vdbeSorterCompare(pCsr, 0, 
+          p1->pVal, p1->nVal, (bKey2InSpace ? 0 : p2->pVal), p2->nVal, &res
       );
       if( rc!=SQLITE_OK ){
         vdbeSorterRecordFree(db, p1);
@@ -507,10 +515,12 @@ static int vdbeSorterMerge(
         *pp = p1;
         pp = &p1->pNext;
         p1 = p1->pNext;
+        bKey2InSpace = 1;
       }else{
         *pp = p2;
         pp = &p2->pNext;
         p2 = p2->pNext;
+        bKey2InSpace = 0;
       }
       *pp = 0;
     }