A proposed fix for the DESC ORDER BY bug of ticket [4dd95f6943fbd18].

Seems to work, but lots more testing is needed prior to moving to trunk.

FossilOrigin-Name: 614a038ad2fe111687d2bc1c0aa716d7eb8fdd7c

manifest

@@ -1,5 +1,5 @@
-C Define\s_BSD_SOURCE\swhen\sbuilding\son\sOpenBSD.\sThis\sis\srequired\sfor\sfchmod().
+C A\sproposed\sfix\sfor\sthe\sDESC\sORDER\sBY\sbug\sof\sticket\s[4dd95f6943fbd18].\nSeems\sto\swork,\sbut\slots\smore\stesting\sis\sneeded\sprior\sto\smoving\sto\strunk.
-D 2013-03-11T13:37:52.519
+D 2013-03-12T18:34:50.356
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 9a804abbd3cae82d196e4d33aba13239e32522a5
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -179,7 +179,7 @@ F src/shell.c 7c41bfcd9e5bf9d96b9215f79b03a5b2b44a3bca
 F src/sqlite.h.in 31045976254225e6bf046a96e87b40fa4c1d55e4
 F src/sqlite3.rc fea433eb0a59f4c9393c8e6d76a6e2596b1fe0c0
 F src/sqlite3ext.h 7183ab832e23db0f934494f16928da127a571d75
-F src/sqliteInt.h 59477c6ddb25e7ed8d8b67f4c58ded254371182e
+F src/sqliteInt.h e390bfafb5d65418555ce2464d5a4ad6e57e8c71
 F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
 F src/status.c bedc37ec1a6bb9399944024d63f4c769971955a9
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -252,7 +252,7 @@ F src/vtab.c b05e5f1f4902461ba9f5fc49bb7eb7c3a0741a83
 F src/wal.c f5c7b5027d0ed0e9bc9afeb4a3a8dfea762ec7d2
 F src/wal.h 29c197540b19044e6cd73487017e5e47a1d3dac6
 F src/walker.c 3d75ba73de15e0f8cd0737643badbeb0e002f07b
-F src/where.c 8b7690cae8700b385d8a53a39387cf8054d8cc47
+F src/where.c 3db35b6231f3da4147294f59e7a1d339c987af32
 F test/8_3_names.test 631ea964a3edb091cf73c3b540f6bcfdb36ce823
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/aggnested.test 45c0201e28045ad38a530b5a144b73cd4aa2cfd6
@@ -1037,7 +1037,10 @@ F tool/vdbe-compress.tcl f12c884766bd14277f4fcedcae07078011717381
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
 F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
-P 1da15adba8f6eec69c24ec6385d6f1a7905a388f
+P f9027cb47bdec8dcebf1f038921b28d9e9928c18
-R 23658f0952d1a2fe0f61c5471a6869f3
+R 095810c67d8046e935e9a69945867a0f
-U dan
+T *branch * desc-orderby-fix-1
-Z 6b791dcdadf138e4fa4768d3023bd490
+T *sym-desc-orderby-fix-1 *
+T -sym-trunk *
+U drh
+Z 8fce222dd4f4c4a0834625ece5c0e872

manifest.uuid

@@ -1 +1 @@
-f9027cb47bdec8dcebf1f038921b28d9e9928c18
+614a038ad2fe111687d2bc1c0aa716d7eb8fdd7c

src/sqliteInt.h

@@ -1931,6 +1931,7 @@ struct WherePlan {
   u32 wsFlags;                   /* WHERE_* flags that describe the strategy */
   u16 nEq;                       /* Number of == constraints */
   u16 nOBSat;                    /* Number of ORDER BY terms satisfied */
+  u16 iOBSat;                    /* First ORDER BY term satisfied */
   double nRow;                   /* Estimated number of rows (for EQP) */
   union {
     Index *pIdx;                   /* Index when WHERE_INDEXED is true */

src/where.c

@@ -1834,6 +1834,7 @@ static void bestOrClauseIndex(WhereBestIdx *p){
         p->cost.used = used;
         p->cost.plan.nRow = nRow;
         p->cost.plan.nOBSat = p->i ? p->aLevel[p->i-1].plan.nOBSat : 0;
+        p->cost.plan.iOBSat = p->cost.plan.nOBSat;
         p->cost.plan.wsFlags = flags;
         p->cost.plan.u.pTerm = pTerm;
       }
@@ -3775,7 +3776,8 @@ static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
 static int codeEqualityTerm(
   Parse *pParse,      /* The parsing context */
   WhereTerm *pTerm,   /* The term of the WHERE clause to be coded */
-  WhereLevel *pLevel, /* When level of the FROM clause we are working on */
+  WhereLevel *pLevel, /* The level of the FROM clause we are working on */
+  int iEq,            /* Index of the equality term within this level */
   int iTarget         /* Attempt to leave results in this register */
 ){
   Expr *pX = pTerm->pExpr;
@@ -3793,8 +3795,15 @@ static int codeEqualityTerm(
     int eType;
     int iTab;
     struct InLoop *pIn;
-    u8 bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0;
+    u8 bRev;
 
+    if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
+      Index *pIdx = pLevel->plan.u.pIdx;
+      bRev = pIdx->aSortOrder[iEq+pLevel->plan.iOBSat];
+    }else{
+      bRev = 0;
+    }
+    if( pLevel->plan.wsFlags & WHERE_REVERSE ) bRev = 1 - bRev;
     assert( pX->op==TK_IN );
     iReg = iTarget;
     eType = sqlite3FindInIndex(pParse, pX, 0);
@@ -3912,7 +3921,7 @@ static int codeAllEqualityTerms(
     ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
     testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
     testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */
-    r1 = codeEqualityTerm(pParse, pTerm, pLevel, regBase+j);
+    r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, regBase+j);
     if( r1!=regBase+j ){
       if( nReg==1 ){
         sqlite3ReleaseTempReg(pParse, regBase);
@@ -4189,7 +4198,7 @@ static Bitmask codeOneLoopStart(
           int iTarget = iReg+j+1;
           pTerm = &pWC->a[aConstraint[k].iTermOffset];
           if( pTerm->eOperator & WO_IN ){
-            codeEqualityTerm(pParse, pTerm, pLevel, iTarget);
+            codeEqualityTerm(pParse, pTerm, pLevel, k, iTarget);
             addrNotFound = pLevel->addrNxt;
           }else{
             sqlite3ExprCode(pParse, pTerm->pExpr->pRight, iTarget);
@@ -4230,7 +4239,7 @@ static Bitmask codeOneLoopStart(
     assert( pTerm->pExpr!=0 );
     assert( omitTable==0 );
     testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */
-    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, iReleaseReg);
+    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, iReleaseReg);
     addrNxt = pLevel->addrNxt;
     sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt);
     sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg);