Evaluate expressions only once when the same expression is used in both the

result set and in the ORDER BY clause.

FossilOrigin-Name: c2f3bbad778504681b39ab9399a1eb3c1a35ab3f

manifest

@@ -1,5 +1,5 @@
-C Refactor\sWith.a.zErr\sinto\sWith.a.zCteErr.\s\sNo\slogic\schanges.
+C Evaluate\sexpressions\sonly\sonce\swhen\sthe\ssame\sexpression\sis\sused\sin\sboth\sthe\nresult\sset\sand\sin\sthe\sORDER\sBY\sclause.
-D 2015-08-26T11:40:11.832
+D 2015-08-26T14:01:41.658
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in e2218eb228374422969de7b1680eda6864affcef
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -289,7 +289,7 @@ F src/ctime.c 5a0b735dc95604766f5dac73973658eef782ee8b
 F src/date.c 8ec787fed4929d8ccdf6b1bc360fccc3e1d2ca58
 F src/dbstat.c f402e77e25089c6003d0c60b3233b9b3947d599a
 F src/delete.c 813be7b5659d7658c8a71b5ae194b45c8f739c8b
-F src/expr.c 650ac7c4f659980a3315e2aaa02a0d71e87f14a5
+F src/expr.c 5944e529891416f482250e16c598d8c26e149eb0
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
 F src/fkey.c 3ce33dd49f12c72376cec9adc7a4d8e7111cedcc
 F src/func.c 824bea430d3a2b7dbc62806ad54da8fdb8ed9e3f
@@ -335,14 +335,14 @@ F src/pragma.h 631a91c8b0e6ca8f051a1d8a4a0da4150e04620a
 F src/prepare.c 82e5db1013846a819f198336fed72c44c974e7b1
 F src/printf.c 2bc439ff20a4aad0e0ad50a37a67b5eae7d20edc
 F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
-F src/resolve.c 66b2740075fdb8baf90155180d33d9850cbcc976
+F src/resolve.c f2ef256786a6435efddd64a632fea89c8be62215
 F src/rowset.c eccf6af6d620aaa4579bd3b72c1b6395d9e9fa1e
-F src/select.c 50b0f02ec4482f92749e6630de9cd0d175a040e1
+F src/select.c b52c80f2b1bdb62491f9ce40eea0c5f80c78d105
 F src/shell.c b1f91e60918df3a68efad1e3a11696b9a7e23d23
 F src/sqlite.h.in 378bebc8fe6a88bade25e5f23b7e6123fdc64b00
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h f700e6a9dd1fdcccc9951ab022b366fb66b9e413
-F src/sqliteInt.h d76e7c90775efeec72ea254a5da0a9f1ddcff765
+F src/sqliteInt.h cac6c31a0c7e6aa5572cc97b68d2630034d6d212
 F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c 51b46b2a62d1b3a959633d593b89bab5e2c9155e
@@ -394,7 +394,7 @@ F src/test_vfstrace.c bab9594adc976cbe696ff3970728830b4c5ed698
 F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
 F src/threads.c 6bbcc9fe50c917864d48287b4792d46d6e873481
 F src/tokenize.c 57cb3720f53f84d811def2069c2b169b6be539a5
-F src/treeview.c 24950c6a79583016c83c43c8b741b3b79a096ce8
+F src/treeview.c 46036cbbceada0836833531b2d963edbca3d9cfa
 F src/trigger.c 322f23aad694e8f31d384dcfa386d52a48d3c52f
 F src/update.c adc8b4b2b6fd2cca2e0d2b803e0cf6956aa3a030
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
@@ -899,6 +899,7 @@ F test/orderby5.test 8f08a54836d21fb7c70245360751aedd1c2286fb
 F test/orderby6.test 8b38138ab0972588240b3fca0985d2e400432859
 F test/orderby7.test 3d1383d52ade5b9eb3a173b3147fdd296f0202da
 F test/orderby8.test 23ef1a5d72bd3adcc2f65561c654295d1b8047bd
+F test/orderby9.test 88a330ea5fc7bed7e407b28beb0d2b79485ae2cc
 F test/oserror.test 14fec2796c2b6fe431c7823750e8a18a761176d7
 F test/ovfl.test 4f7ca651cba5c059a12d8c67dddd49bec5747799
 F test/pager1.test 1acbdb14c5952a72dd43129cabdbf69aaa3ed1fa
@@ -1379,7 +1380,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 65a8918776aa395009a690fa86bfc7d99eb973f9
+P 58ba73630ecc4bc58b03a7962dd45b305ef605ef
-R a6b3114ece5e49154c10e2c8118e9866
+R 657299463d01da646731fb6b8ab7d9fe
 U drh
-Z b1a98f3cfbd2154f3cffafb179efca91
+Z 83e3936f8767c9500521d2082aa870a1

manifest.uuid

@@ -1 +1 @@
-58ba73630ecc4bc58b03a7962dd45b305ef605ef
+c2f3bbad778504681b39ab9399a1eb3c1a35ab3f

src/expr.c

@@ -2912,7 +2912,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
         }
 
         sqlite3ExprCachePush(pParse);     /* Ticket 2ea2425d34be */
-        sqlite3ExprCodeExprList(pParse, pFarg, r1,
+        sqlite3ExprCodeExprList(pParse, pFarg, r1, 0,
                                 SQLITE_ECEL_DUP|SQLITE_ECEL_FACTOR);
         sqlite3ExprCachePop(pParse);      /* Ticket 2ea2425d34be */
       }else{
@@ -3328,11 +3328,13 @@ int sqlite3ExprCodeExprList(
   Parse *pParse,     /* Parsing context */
   ExprList *pList,   /* The expression list to be coded */
   int target,        /* Where to write results */
+  int srcReg,        /* Source registers if SQLITE_ECEL_REF */
   u8 flags           /* SQLITE_ECEL_* flags */
 ){
   struct ExprList_item *pItem;
-  int i, n;
+  int i, j, n;
   u8 copyOp = (flags & SQLITE_ECEL_DUP) ? OP_Copy : OP_SCopy;
+  Vdbe *v = pParse->pVdbe;
   assert( pList!=0 );
   assert( target>0 );
   assert( pParse->pVdbe!=0 );  /* Never gets this far otherwise */
@@ -3340,13 +3342,14 @@ int sqlite3ExprCodeExprList(
   if( !ConstFactorOk(pParse) ) flags &= ~SQLITE_ECEL_FACTOR;
   for(pItem=pList->a, i=0; i<n; i++, pItem++){
     Expr *pExpr = pItem->pExpr;
-    if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
+    if( (flags & SQLITE_ECEL_REF)!=0 && (j = pList->a[i].u.x.iOrderByCol)>0 ){
+      sqlite3VdbeAddOp2(v, copyOp, j+srcReg-1, target+i);
+    }else if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
       sqlite3ExprCodeAtInit(pParse, pExpr, target+i, 0);
     }else{
       int inReg = sqlite3ExprCodeTarget(pParse, pExpr, target+i);
       if( inReg!=target+i ){
         VdbeOp *pOp;
-        Vdbe *v = pParse->pVdbe;
         if( copyOp==OP_Copy
          && (pOp=sqlite3VdbeGetOp(v, -1))->opcode==OP_Copy
          && pOp->p1+pOp->p3+1==inReg

src/resolve.c

@@ -407,9 +407,9 @@ static int lookupName(
     ** resolved by the time the WHERE clause is resolved.
     **
     ** The ability to use an output result-set column in the WHERE, GROUP BY,
-    ** or HAVING clauses, or as part of a larger expression in the ORDRE BY
+    ** or HAVING clauses, or as part of a larger expression in the ORDER BY
     ** clause is not standard SQL.  This is a (goofy) SQLite extension, that
-    ** is supported for backwards compatibility only.  TO DO: Issue a warning
+    ** is supported for backwards compatibility only. Hence, we issue a warning
     ** on sqlite3_log() whenever the capability is used.
     */
     if( (pEList = pNC->pEList)!=0

src/select.c

@@ -496,6 +496,7 @@ static void pushOntoSorter(
   SortCtx *pSort,        /* Information about the ORDER BY clause */
   Select *pSelect,       /* The whole SELECT statement */
   int regData,           /* First register holding data to be sorted */
+  int regOrigData,       /* First register holding data before packing */
   int nData,             /* Number of elements in the data array */
   int nPrefixReg         /* No. of reg prior to regData available for use */
 ){
@@ -509,6 +510,7 @@ static void pushOntoSorter(
   int op;                            /* Opcode to add sorter record to sorter */
 
   assert( bSeq==0 || bSeq==1 );
+  assert( nData==1 || regData==regOrigData );
   if( nPrefixReg ){
     assert( nPrefixReg==nExpr+bSeq );
     regBase = regData - nExpr - bSeq;
@@ -516,7 +518,8 @@ static void pushOntoSorter(
     regBase = pParse->nMem + 1;
     pParse->nMem += nBase;
   }
-  sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, SQLITE_ECEL_DUP);
+  sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
+                          SQLITE_ECEL_DUP|SQLITE_ECEL_REF);
   if( bSeq ){
     sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
   }
@@ -726,7 +729,7 @@ static void selectInnerLoop(
     }else{
       ecelFlags = 0;
     }
-    sqlite3ExprCodeExprList(pParse, pEList, regResult, ecelFlags);
+    sqlite3ExprCodeExprList(pParse, pEList, regResult, 0, ecelFlags);
   }
 
   /* If the DISTINCT keyword was present on the SELECT statement
@@ -842,7 +845,7 @@ static void selectInnerLoop(
       }
 #endif
       if( pSort ){
-        pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, 1, nPrefixReg);
+        pushOntoSorter(pParse, pSort, p, r1+nPrefixReg,regResult,1,nPrefixReg);
       }else{
         int r2 = sqlite3GetTempReg(pParse);
         sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
@@ -868,7 +871,7 @@ static void selectInnerLoop(
         ** ORDER BY in this case since the order of entries in the set
         ** does not matter.  But there might be a LIMIT clause, in which
         ** case the order does matter */
-        pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg);
+        pushOntoSorter(pParse, pSort, p, regResult, regResult, 1, nPrefixReg);
       }else{
         int r1 = sqlite3GetTempReg(pParse);
         sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult,1,r1, &pDest->affSdst, 1);
@@ -894,7 +897,7 @@ static void selectInnerLoop(
     case SRT_Mem: {
       assert( nResultCol==1 );
       if( pSort ){
-        pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg);
+        pushOntoSorter(pParse, pSort, p, regResult, regResult, 1, nPrefixReg);
       }else{
         assert( regResult==iParm );
         /* The LIMIT clause will jump out of the loop for us */
@@ -908,7 +911,8 @@ static void selectInnerLoop(
       testcase( eDest==SRT_Coroutine );
       testcase( eDest==SRT_Output );
       if( pSort ){
-        pushOntoSorter(pParse, pSort, p, regResult, nResultCol, nPrefixReg);
+        pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol,
+                       nPrefixReg);
       }else if( eDest==SRT_Coroutine ){
         sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
       }else{
@@ -4667,7 +4671,7 @@ static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
     if( pList ){
       nArg = pList->nExpr;
       regAgg = sqlite3GetTempRange(pParse, nArg);
-      sqlite3ExprCodeExprList(pParse, pList, regAgg, SQLITE_ECEL_DUP);
+      sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP);
     }else{
       nArg = 0;
       regAgg = 0;
@@ -5287,7 +5291,7 @@ int sqlite3Select(
         }
         regBase = sqlite3GetTempRange(pParse, nCol);
         sqlite3ExprCacheClear(pParse);
-        sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0);
+        sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0);
         j = nGroupBy;
         for(i=0; i<sAggInfo.nColumn; i++){
           struct AggInfo_col *pCol = &sAggInfo.aCol[i];

src/sqliteInt.h

@@ -3376,9 +3376,10 @@ void sqlite3ExprCodeAtInit(Parse*, Expr*, int, u8);
 int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
 int sqlite3ExprCodeTarget(Parse*, Expr*, int);
 void sqlite3ExprCodeAndCache(Parse*, Expr*, int);
-int sqlite3ExprCodeExprList(Parse*, ExprList*, int, u8);
+int sqlite3ExprCodeExprList(Parse*, ExprList*, int, int, u8);
 #define SQLITE_ECEL_DUP      0x01  /* Deep, not shallow copies */
 #define SQLITE_ECEL_FACTOR   0x02  /* Factor out constant terms */
+#define SQLITE_ECEL_REF      0x04  /* Use ExprList.u.x.iOrderByCol */
 void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
 void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
 void sqlite3ExprIfFalseDup(Parse*, Expr*, int, int);

src/treeview.c

@@ -432,7 +432,13 @@ void sqlite3TreeViewExprList(
   }else{
     sqlite3TreeViewLine(pView, "%s", zLabel);
     for(i=0; i<pList->nExpr; i++){
+      int j = pList->a[i].u.x.iOrderByCol;
+      if( j ){
+        sqlite3TreeViewPush(pView, 0);
+        sqlite3TreeViewLine(pView, "iOrderByCol=%d", j);
+      }
       sqlite3TreeViewExpr(pView, pList->a[i].pExpr, i<pList->nExpr-1);
+      if( j ) sqlite3TreeViewPop(pView);
     }
   }
   sqlite3TreeViewPop(pView);

test/orderby9.test

@@ -0,0 +1,52 @@
+# 2015-08-26
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.
+# 
+# This file seeks to verify that expressions (and especially functions)
+# that are in both the ORDER BY clause and the result set are only
+# evaluated once.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set ::testprefix orderby9
+
+
+do_execsql_test setup {
+  -- create a table with many entries
+  CREATE TABLE t1(x);
+  WITH RECURSIVE
+     c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<100)
+  INSERT INTO t1 SELECT x FROM c;
+}
+do_test 1.0 {
+  set l1 {}
+  # If random() is only evaluated once and then reused for each row, then
+  # the output should appear in sorted order.  If random() is evaluated 
+  # separately for the result set and the ORDER BY clause, then the output
+  # order will be random.
+  db eval {SELECT random() AS y FROM t1 ORDER BY 1;} {lappend l1 $y}
+  expr {$l1==[lsort -int $l1]}
+} {1}
+
+do_test 1.1 {
+  set l1 {}
+  db eval {SELECT random() AS y FROM t1 ORDER BY random();} {lappend l1 $y}
+  expr {$l1==[lsort -int $l1]}
+} {1}
+
+do_test 1.2 {
+  set l1 {}
+  db eval {SELECT random() AS y FROM t1 ORDER BY +random();} {lappend l1 $y}
+  expr {$l1==[lsort -int $l1]}
+} {0}
+
+finish_test