Experimental changes to help the query planner detect when an expression

index is coverting.  Works somewhat, but there are tests that fail.

FossilOrigin-Name: 968c189bcf29a9b25305251a58d09b7d52ab9dd08f5057dc3ab1f7ad1a5316a0

manifest

@@ -1,5 +1,5 @@
-C Relax\srestriction\s(8)\son\sthe\spush-down\soptimization\sso\sthat\sit\sonly\sapplies\nif\sone\sor\smore\scolumns\suses\sa\scollating\ssequence\sother\sthan\sBINARY.\nSee\s[forum:/forumpost/3824ced748baa808|forum\spost\s3824ced748baa808]\sand\ncheck-in\s[346a3b12b861ce7b].
-D 2022-11-25T17:05:55.692
+C Experimental\schanges\sto\shelp\sthe\squery\splanner\sdetect\swhen\san\sexpression\nindex\sis\scoverting.\s\sWorks\ssomewhat,\sbut\sthere\sare\stests\sthat\sfail.
+D 2022-11-26T14:19:47.899
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -728,7 +728,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c b9df133a705093da8977da5eb202eaadb844839f1c7297c08d33471f5491843d
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c ea0f518df9e00aa44013a1d384090b4b3a499ee11d4daa0a7d99c4eb9f7ab4ba
+F src/where.c 550388b75a29c2af2c2182e56e2a51bc6b92aef302eb072f177b3526394d6020
 F src/whereInt.h df0c79388c0b71b4a91f480d02791679fe0345d40410435c541c8893e95a4d3f
 F src/wherecode.c 133a94f82858787217d073143617df19e4a6a7d0b771a1519f957608109ad5a5
 F src/whereexpr.c 05295b44b54eea76d1ba766f0908928d0e20e990c249344c9521454d3d09c7ae
@@ -2060,8 +2060,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 09e1e42e0ff26f9a71cbd128169f060a66425828d637bf8f781490ca38d99103
-R 051f7bebeb695c93dfdb45030ad5b532
+P adbca3448e2099f0d6149a073978f230ed9a92a2f384779879ef89e672231bcf
+R b02bf662fd2aa7710f36a7d19197692a
+T *branch * covering-indexed-expr
+T *sym-covering-indexed-expr *
+T -sym-trunk *
 U drh
-Z 0a4a218169578e69e7b7469760b002aa
+Z e78db49817bfc2647feb4d11db6b69e2
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-adbca3448e2099f0d6149a073978f230ed9a92a2f384779879ef89e672231bcf
+968c189bcf29a9b25305251a58d09b7d52ab9dd08f5057dc3ab1f7ad1a5316a0

src/where.c

@@ -3247,6 +3247,26 @@ static int whereUsablePartialIndex(
   return 0;
 }
 
+/*
+** pIdx is an index containing expressions.  Check it see if any of the
+** expressions in the index match the pExpr expression.
+*/
+static int exprIsCoveredByIndex(
+  const Expr *pExpr,
+  const Index *pIdx,
+  int iTabCur
+){
+  int i;
+  for(i=0; i<pIdx->nColumn; i++){
+    if( pIdx->aiColumn[i]==XN_EXPR
+     && sqlite3ExprCompare(0, pExpr, pIdx->aColExpr->a[i].pExpr, iTabCur)==0
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
 /*
 ** Structure passed to the whereIsCoveringIndex Walker callback.
 */
@@ -3256,7 +3276,7 @@ struct CoveringIndexCheck {
 };
 
 /*
-** Information passed in is pWalk->u.pCovIdxCk.  Call is pCk.
+** Information passed in is pWalk->u.pCovIdxCk.  Call it pCk.
 **
 ** If the Expr node references the table with cursor pCk->iTabCur, then
 ** make sure that column is covered by the index pCk->pIdx.  We know that
@@ -3268,23 +3288,32 @@ struct CoveringIndexCheck {
 **
 ** If this node does not disprove that the index can be a covering index,
 ** then just return WRC_Continue, to continue the search.
+**
+** If pCk->pIdx contains indexed expressions and one of those expressions
+** matches pExpr, then prune the search.
 */
 static int whereIsCoveringIndexWalkCallback(Walker *pWalk, Expr *pExpr){
   int i;                  /* Loop counter */
   const Index *pIdx;      /* The index of interest */
   const i16 *aiColumn;    /* Columns contained in the index */
   u16 nColumn;            /* Number of columns in the index */
-  if( pExpr->op!=TK_COLUMN && pExpr->op!=TK_AGG_COLUMN ) return WRC_Continue;
-  if( pExpr->iColumn<(BMS-1) ) return WRC_Continue;
-  if( pExpr->iTable!=pWalk->u.pCovIdxCk->iTabCur ) return WRC_Continue;
   pIdx = pWalk->u.pCovIdxCk->pIdx;
-  aiColumn = pIdx->aiColumn;
-  nColumn = pIdx->nColumn;
-  for(i=0; i<nColumn; i++){
-    if( aiColumn[i]==pExpr->iColumn ) return WRC_Continue;
+  if( (pExpr->op==TK_COLUMN || pExpr->op==TK_AGG_COLUMN) ){
+    /* if( pExpr->iColumn<(BMS-1) && pIdx->bHasExpr==0 ) return WRC_Continue;*/
+    if( pExpr->iTable!=pWalk->u.pCovIdxCk->iTabCur ) return WRC_Continue;
+    pIdx = pWalk->u.pCovIdxCk->pIdx;
+    aiColumn = pIdx->aiColumn;
+    nColumn = pIdx->nColumn;
+    for(i=0; i<nColumn; i++){
+      if( aiColumn[i]==pExpr->iColumn ) return WRC_Continue;
+    }
+    pWalk->eCode = 1;
+    return WRC_Abort;
+  }else if( pIdx->bHasExpr
+         && exprIsCoveredByIndex(pExpr, pIdx, pWalk->u.pCovIdxCk->iTabCur) ){
+    return WRC_Prune;
   }
-  pWalk->eCode = 1;
-  return WRC_Abort;
+  return WRC_Continue;
 }
 
 
@@ -3315,14 +3344,16 @@ static SQLITE_NOINLINE u32 whereIsCoveringIndex(
     ** if pIdx is covering.  Assume it is not. */
     return 1;
   }
-  for(i=0; i<pIdx->nColumn; i++){
-    if( pIdx->aiColumn[i]>=BMS-1 ) break;
-  }
-  if( i>=pIdx->nColumn ){
-    /* pIdx does not index any columns greater than 62, but we know from
-    ** colMask that columns greater than 62 are used, so this is not a
-    ** covering index */
-    return 1;
+  if( pIdx->bHasExpr==0 ){
+    for(i=0; i<pIdx->nColumn; i++){
+      if( pIdx->aiColumn[i]>=BMS-1 ) break;
+    }
+    if( i>=pIdx->nColumn ){
+      /* pIdx does not index any columns greater than 62, but we know from
+      ** colMask that columns greater than 62 are used, so this is not a
+      ** covering index */
+      return 1;
+    }
   }
   ck.pIdx = pIdx;
   ck.iTabCur = iTabCur;
@@ -3552,7 +3583,7 @@ static int whereLoopAddBtree(
         m = 0;
       }else{
         m = pSrc->colUsed & pProbe->colNotIdxed;
-        if( m==TOPBIT ){
+        if( m==TOPBIT || pProbe->bHasExpr ){
           m = whereIsCoveringIndex(pWInfo, pProbe, pSrc->iCursor);
         }
         pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;