Improved handling of constants and especially constant functions in the

ORDER BY clause of a query.  Do not optimize out "ORDER BY random()".
Fix for ticket [65bdeb9739605cc2296].

FossilOrigin-Name: dca1945aeb3fb005263f9be00ee8e72b966ae303

manifest

@@ -1,5 +1,5 @@
-C Do\snot\sallow\stemporary\sregisters\sto\sbe\sin\suse\sacross\san\sOP_Yield\swithin\sa\nco-routine.\s\sFix\sfor\sticket\s[8c63ff0eca81a9132d8].
-D 2014-02-25T21:55:16.402
+C Improved\shandling\sof\sconstants\sand\sespecially\sconstant\sfunctions\sin\sthe\nORDER\sBY\sclause\sof\sa\squery.\s\sDo\snot\soptimize\sout\s"ORDER\sBY\srandom()".\nFix\sfor\sticket\s[65bdeb9739605cc2296].
+D 2014-02-26T02:26:09.921
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -290,7 +290,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 76e7fc6de229bea8b30bb2539110f03a494dc3a8
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
-F src/where.c 0b5a4d45fdf05ad541893d986abd2f660f6e0094
+F src/where.c 6042e1a377cf7dc72c10493269ed75e276275cd8
 F src/whereInt.h 921f935af8b684ffb49705610bda7284db1db138
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -1070,7 +1070,7 @@ F test/walshared.test 0befc811dcf0b287efae21612304d15576e35417
 F test/walslow.test e7be6d9888f83aa5d3d3c7c08aa9b5c28b93609a
 F test/walthread.test de8dbaf6d9e41481c460ba31ca61e163d7348f8e
 F test/where.test 28b64e93428961b07b0d486778d63fd672948f6b
-F test/where2.test ed6baa9420a109d8be683dbef5d153d186f3690b
+F test/where2.test 455a2eb2666e66c1e84e2cb5815173a85e6237db
 F test/where3.test d28c51f257e60be30f74308fa385ceeddfb54a6e
 F test/where4.test d8420ceeb8323a41ceff1f1841fc528e824e1ecf
 F test/where5.test fdf66f96d29a064b63eb543e28da4dfdccd81ad2
@@ -1152,7 +1152,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 23001a85cd334090cf6c70d4d7e722a01f4f6899
-R 53d871612a374a058c13125cf02ae108
+P 97a8c9733cba97c78e979dfd5c66610c23e90288
+R a3177866e2afe2abf843086af2a9a3a2
 U drh
-Z 196bbfe69fc9298304e0610559f3cd1e
+Z c50f86b62c93dcd00c53d2ca75883787

manifest.uuid

@@ -1 +1 @@
-97a8c9733cba97c78e979dfd5c66610c23e90288
+dca1945aeb3fb005263f9be00ee8e72b966ae303

src/where.c

@@ -4901,9 +4901,12 @@ static int wherePathSatisfiesOrderBy(
       orderDistinctMask |= pLoop->maskSelf;
       for(i=0; i<nOrderBy; i++){
         Expr *p;
+        Bitmask mTerm;
         if( MASKBIT(i) & obSat ) continue;
         p = pOrderBy->a[i].pExpr;
-        if( (exprTableUsage(&pWInfo->sMaskSet, p)&~orderDistinctMask)==0 ){
+        mTerm = exprTableUsage(&pWInfo->sMaskSet,p);
+        if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
+        if( (mTerm&~orderDistinctMask)==0 ){
           obSat |= MASKBIT(i);
         }
       }
@@ -5526,22 +5529,6 @@ WhereInfo *sqlite3WhereBegin(
     goto whereBeginError;
   }
 
-  /* If the ORDER BY (or GROUP BY) clause contains references to general
-  ** expressions, then we won't be able to satisfy it using indices, so
-  ** go ahead and disable it now.
-  */
-  if( pOrderBy && (wctrlFlags & WHERE_WANT_DISTINCT)!=0 ){
-    for(ii=0; ii<pOrderBy->nExpr; ii++){
-      Expr *pExpr = sqlite3ExprSkipCollate(pOrderBy->a[ii].pExpr);
-      if( pExpr->op!=TK_COLUMN ){
-        pWInfo->pOrderBy = pOrderBy = 0;
-        break;
-      }else if( pExpr->iColumn<0 ){
-        break;
-      }
-    }
-  }
-
   if( wctrlFlags & WHERE_WANT_DISTINCT ){
     if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
       /* The DISTINCT marking is pointless.  Ignore it. */

test/where2.test

@@ -121,6 +121,42 @@ do_test where2-2.3 {
   }
 } {85 6 7396 7402 nosort t1 *}
 
+# Ticket [65bdeb9739605cc22966f49208452996ff29a640] 2014-02-26
+# Make sure "ORDER BY random" does not gets optimized out.
+#
+do_test where2-2.4 {
+  db eval {
+    CREATE TABLE x1(a INTEGER PRIMARY KEY, b DEFAULT 1);
+    WITH RECURSIVE
+       cnt(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM cnt WHERE x<50)
+    INSERT INTO x1 SELECT x, 1 FROM cnt;
+    CREATE TABLE x2(x INTEGER PRIMARY KEY);
+    INSERT INTO x2 VALUES(1);
+  }
+  set sql {SELECT * FROM x1, x2 WHERE x=1 ORDER BY random()}
+  set out1 [db eval $sql]
+  set out2 [db eval $sql]
+  set out3 [db eval $sql]
+  expr {$out1!=$out2 && $out2!=$out3}
+} {1}
+do_execsql_test where2-2.5 {
+  -- random() is not optimized out
+  EXPLAIN SELECT * FROM x1, x2 WHERE x=1 ORDER BY random();
+} {/ random/}
+do_execsql_test where2-2.5b {
+  -- random() is not optimized out
+  EXPLAIN SELECT * FROM x1, x2 WHERE x=1 ORDER BY random();
+} {/ SorterOpen /}
+do_execsql_test where2-2.6 {
+  -- other constant functions are optimized out
+  EXPLAIN SELECT * FROM x1, x2 WHERE x=1 ORDER BY abs(5);
+} {~/ abs/}
+do_execsql_test where2-2.6b {
+  -- other constant functions are optimized out
+  EXPLAIN SELECT * FROM x1, x2 WHERE x=1 ORDER BY abs(5);
+} {~/ SorterOpen /}
+
+
 
 # Efficient handling of forward and reverse table scans.
 #