Reenable the SQLITE_EXPR_REF optimization for "SELECT DISTINCT ... ORDER BY"

queries.

FossilOrigin-Name: 6e2e9d383f5fc4a0cbf05fe83ec7425812c0f556

manifest

@@ -1,5 +1,5 @@
-C Avoid\sstoring\sredundant\sfields\sin\ssorter\srecords\swhen\sthe\ssort-key\sand\sdata\shave\nfields\sin\scommon\s(as\sin\s"SELECT\sa\sFROM\st1\sORDER\sBY\s1").
+C Reenable\sthe\sSQLITE_EXPR_REF\soptimization\sfor\s"SELECT\sDISTINCT\s...\sORDER\sBY"\nqueries.
-D 2016-11-10T20:14:06.787
+D 2016-11-11T18:08:59.063
 F Makefile.in 6fd48ffcf7c2deea7499062d1f3747f986c19678
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc e0217f2d35a0448abbe4b066132ae20136e8b408
@@ -387,7 +387,7 @@ F src/printf.c a5f0ca08ddede803c241266abb46356ec748ded1
 F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
 F src/resolve.c 3fac1b2737ea5a724f20b921ac7e259c9be2100b
 F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
-F src/select.c 64b2273747c6485638bfeb6790e3e774e0605d02
+F src/select.c 04fd717fb99aea2110b752e2b6186b966fa13cb4
 F src/shell.c 63e54cfa1c7ec5b70a4c9a86502bc10280c3d5a3
 F src/sqlite.h.in 803f7050f69b2eea573fac219f3c92582c096027
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1530,10 +1530,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b4889588246c33374ff3758e21ccc4ce246380b6
+P 0af62fdbd8e2aab14718ff8bcb5934f05463c176
-R e8a5368c67459f65dc206ad3df15a284
+R dccdf5cb21f8816d64d778a9f6efd1e8
-T *branch * sorter-opt
-T *sym-sorter-opt *
-T -sym-trunk *
 U dan
-Z 220ba0a8da96dcdf18555b62136e6fa1
+Z 74767a1cb4eda88af63e605e54888e92

manifest.uuid

@@ -1 +1 @@
-0af62fdbd8e2aab14718ff8bcb5934f05463c176
+6e2e9d383f5fc4a0cbf05fe83ec7425812c0f556

src/select.c

@@ -521,7 +521,7 @@ static void pushOntoSorter(
   int iLimit;                        /* LIMIT counter */
 
   assert( bSeq==0 || bSeq==1 );
-  assert( nData==1 || regData==regOrigData );
+  assert( nData==1 || regData==regOrigData || regOrigData==0 );
   if( nPrefixReg ){
     assert( nPrefixReg==nExpr+bSeq );
     regBase = regData - nExpr - bSeq;
@@ -533,7 +533,7 @@ static void pushOntoSorter(
   iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
   pSort->labelDone = sqlite3VdbeMakeLabel(v);
   sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
-                          SQLITE_ECEL_DUP);
+                          SQLITE_ECEL_DUP | (regOrigData? SQLITE_ECEL_REF : 0));
   if( bSeq ){
     sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
   }
@@ -681,13 +681,20 @@ static void selectInnerLoop(
 ){
   Vdbe *v = pParse->pVdbe;
   int i;
-  int hasDistinct;        /* True if the DISTINCT keyword is present */
+  int hasDistinct;            /* True if the DISTINCT keyword is present */
-  int regResult;              /* Start of memory holding result set */
   int eDest = pDest->eDest;   /* How to dispose of results */
   int iParm = pDest->iSDParm; /* First argument to disposal method */
   int nResultCol;             /* Number of result columns */
   int nPrefixReg = 0;         /* Number of extra registers before regResult */
 
+  /* Usually, regResult is the first cell in an array of memory cells
+  ** containing the current result row. In this case regOrig is set to the
+  ** same value. However, if the results are being sent to the sorter, the
+  ** values for any expressions that are also part of the sort-key are omitted
+  ** from this array. In this case regOrig is set to zero.  */
+  int regResult;              /* Start of memory holding current results */
+  int regOrig;                /* Start of memory holding full result (or 0) */
+
   assert( v );
   assert( pEList!=0 );
   hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
@@ -718,7 +725,7 @@ static void selectInnerLoop(
     pParse->nMem += nResultCol;
   }
   pDest->nSdst = nResultCol;
-  regResult = pDest->iSdst;
+  regOrig = regResult = pDest->iSdst;
   if( srcTab>=0 ){
     for(i=0; i<nResultCol; i++){
       sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
@@ -734,7 +741,8 @@ static void selectInnerLoop(
     }else{
       ecelFlags = 0;
     }
-    if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
+    assert( eDest!=SRT_Table || pSort==0 );
+    if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab ){
       /* For each expression in pEList that is a copy of an expression in
       ** the ORDER BY clause (pSort->pOrderBy), set the associated 
       ** iOrderByCol value to one more than the index of the ORDER BY 
@@ -748,7 +756,7 @@ static void selectInnerLoop(
           pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
         }
       }
-
+      regOrig = 0;
       assert( eDest==SRT_Set || eDest==SRT_Mem 
            || eDest==SRT_Coroutine || eDest==SRT_Output );
     }
@@ -892,7 +900,7 @@ static void selectInnerLoop(
         ** does not matter.  But there might be a LIMIT clause, in which
         ** case the order does matter */
         pushOntoSorter(
-            pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
+            pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
       }else{
         int r1 = sqlite3GetTempReg(pParse);
         assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol );
@@ -921,7 +929,7 @@ static void selectInnerLoop(
       if( pSort ){
         assert( nResultCol<=pDest->nSdst );
         pushOntoSorter(
-            pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
+            pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
       }else{
         assert( nResultCol==pDest->nSdst );
         assert( regResult==iParm );
@@ -936,7 +944,7 @@ static void selectInnerLoop(
       testcase( eDest==SRT_Coroutine );
       testcase( eDest==SRT_Output );
       if( pSort ){
-        pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol,
+        pushOntoSorter(pParse, pSort, p, regResult, regOrig, nResultCol,
                        nPrefixReg);
       }else if( eDest==SRT_Coroutine ){
         sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);