Merge the vdbesort.c optimization from trunk.

FossilOrigin-Name: e4bfffb988283c077778c60696be0d285ad66c3c

manifest

@@ -1,5 +1,5 @@
-C Fix\squery\splanner\sweights\sassociated\swith\schoosing\sblock-sorting.\s\sFix\nblock\ssorting\sof\stables\swith\scollating\sfunctions.\s\sFix\svarious\stest\scases.\nAll\s"veryquick"\stests\sare\snow\spassing,\sthough\smore\stests\sneed\sto\sbe\sadded.
-D 2014-03-19T23:24:49.240
+C Merge\sthe\svdbesort.c\soptimization\sfrom\strunk.
+D 2014-03-19T23:42:51.606
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -285,7 +285,7 @@ F src/vdbeapi.c 0ed6053f947edd0b30f64ce5aeb811872a3450a4
 F src/vdbeaux.c 5078ca7de4fd5ba4535bd17fe44d5b56c2d3294c
 F src/vdbeblob.c 15377abfb59251bccedd5a9c7d014a895f0c04aa
 F src/vdbemem.c 6fc77594c60f6155404f3f8d71bf36d1fdeb4447
-F src/vdbesort.c 553537f632e8925bb8a2563692d0ee6e2175018c
+F src/vdbesort.c 17336685efeef61170485b273cb14b3f1c68130e
 F src/vdbetrace.c 6f52bc0c51e144b7efdcfb2a8f771167a8816767
 F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 76e7fc6de229bea8b30bb2539110f03a494dc3a8
@@ -1156,7 +1156,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 7ce2daafd39a117041bfdd0a7132e2764fe7a74b
-R f3bf694b0186fa15aaedfb1a5982c72f
+P 01afbf97c0ff29667806e9a7c4d74ca717819de5 707ea170b3e26965b7e3982f7554d122d130b9a6
+R 8822581e4a84d2f390bdca26ebdb6cc0
 U drh
-Z 15ce545d4c6482a35d82cbe6b958fe2e
+Z db1037b5faa49e6de7af132643ccdf5b

manifest.uuid

@@ -1 +1 @@
-01afbf97c0ff29667806e9a7c4d74ca717819de5
+e4bfffb988283c077778c60696be0d285ad66c3c

src/vdbesort.c

@@ -973,14 +973,55 @@ int sqlite3VdbeSorterNext(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
 
   if( pSorter->aTree ){
     int iPrev = pSorter->aTree[1];/* Index of iterator to advance */
-    int i;                        /* Index of aTree[] to recalculate */
-
     rc = vdbeSorterIterNext(db, &pSorter->aIter[iPrev]);
-    for(i=(pSorter->nTree+iPrev)/2; rc==SQLITE_OK && i>0; i=i/2){
-      rc = vdbeSorterDoCompare(pCsr, i);
-    }
+    if( rc==SQLITE_OK ){
+      int i;                      /* Index of aTree[] to recalculate */
+      VdbeSorterIter *pIter1;     /* First iterator to compare */
+      VdbeSorterIter *pIter2;     /* Second iterator to compare */
+      u8 *pKey2;                  /* To pIter2->aKey, or 0 if record cached */
 
-    *pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0);
+      /* Find the first two iterators to compare. The one that was just
+      ** advanced (iPrev) and the one next to it in the array.  */
+      pIter1 = &pSorter->aIter[(iPrev & 0xFFFE)];
+      pIter2 = &pSorter->aIter[(iPrev | 0x0001)];
+      pKey2 = pIter2->aKey;
+
+      for(i=(pSorter->nTree+iPrev)/2; i>0; i=i/2){
+        /* Compare pIter1 and pIter2. Store the result in variable iRes. */
+        int iRes;
+        if( pIter1->pFile==0 ){
+          iRes = +1;
+        }else if( pIter2->pFile==0 ){
+          iRes = -1;
+        }else{
+          vdbeSorterCompare(pCsr, 0, 
+              pIter1->aKey, pIter1->nKey, pKey2, pIter2->nKey, &iRes
+          );
+        }
+
+        /* If pIter1 contained the smaller value, set aTree[i] to its index.
+        ** Then set pIter2 to the next iterator to compare to pIter1. In this
+        ** case there is no cache of pIter2 in pSorter->pUnpacked, so set
+        ** pKey2 to point to the record belonging to pIter2.
+        **
+        ** Alternatively, if pIter2 contains the smaller of the two values,
+        ** set aTree[i] to its index and update pIter1. If vdbeSorterCompare()
+        ** was actually called above, then pSorter->pUnpacked now contains
+        ** a value equivalent to pIter2. So set pKey2 to NULL to prevent
+        ** vdbeSorterCompare() from decoding pIter2 again.  */
+        if( iRes<=0 ){
+          pSorter->aTree[i] = (pIter1 - pSorter->aIter);
+          pIter2 = &pSorter->aIter[ pSorter->aTree[i ^ 0x0001] ];
+          pKey2 = pIter2->aKey;
+        }else{
+          if( pIter1->pFile ) pKey2 = 0;
+          pSorter->aTree[i] = (pIter2 - pSorter->aIter);
+          pIter1 = &pSorter->aIter[ pSorter->aTree[i ^ 0x0001] ];
+        }
+
+      }
+      *pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0);
+    }
   }else{
     SorterRecord *pFree = pSorter->pRecord;
     pSorter->pRecord = pFree->pNext;