Avoid materializing columns of SF_NestedFrom subqueries that are never used.

Other code improvements manually imported from the right-join-paren branch.

FossilOrigin-Name: cd8272fc2a34d1b245fd95208b9b601266ee7d2ff0f5ce52d03752f2c4e852a2

diff --git a/manifest b/manifest
index cc8af505d8df08440667f6a41e6d28ba0bc8dbd5..e4a592253d2c8744118ad2d9eea577575536c342 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Small\scorrection\sto\sthe\snew\sbUsed\slogic\sof\ssqlite3ProcessJoin().
-D 2022-04-20T18:12:42.455
+C Avoid\smaterializing\scolumns\sof\sSF_NestedFrom\ssubqueries\sthat\sare\snever\sused.\nOther\scode\simprovements\smanually\simported\sfrom\sthe\sright-join-paren\sbranch.
+D 2022-04-21T13:11:26.388
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -503,7 +503,7 @@ F src/date.c 15082566229d4b1e5f24fdb490bf9bcc68824b911d70e3573ef075a1b9e2d26f
 F src/dbpage.c 90661a87e1db8bfbc8d2ebbdcd3749651ddb287c555c07a28fb17c7c591ffb68
 F src/dbstat.c 861e08690fcb0f2ee1165eff0060ea8d4f3e2ea10f80dab7d32ad70443a6ff2d
 F src/delete.c a8e844af211a48b13b5b358be77a12c860c6a557c21990ad51a548e2536500ce
-F src/expr.c 0714987d576d13acb64630274677ff0df336013bf83dfc1ff24a339b8ae2ae81
+F src/expr.c 899c77da1cd4d836d93f94cf435fc761695938dda8932becfccfdb2eb7d6a7d9
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c d965ede15d8360c09ed59348940649ee647b192e784466837d7aefa836d1d91e
 F src/func.c a3407a6fbb0d4088d8d502e46f0ace63e0aeae7467ae23a9ca9815bbf9239761
@@ -550,9 +550,9 @@ F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c fd940149c691684e7c1073c3787a7170e44852b02d1275d2e30a5b58e89cfcaf
 F src/printf.c 05d8dfd2018bc4fc3ddb8b37eb97ccef7abf985643fa1caebdcf2916ca90fa32
 F src/random.c 097dc8b31b8fba5a9aca1697aeb9fd82078ec91be734c16bffda620ced7ab83c
-F src/resolve.c 4039e3d89af416ffa8d665b59aac53ccdb10e088d8017649f2ceabda5e73473b
+F src/resolve.c f72bb13359dd5a74d440df25f320dc2c1baff5cde4fc9f0d1bc3feba90b8932a
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c 8978bab868e63781d91d0b689b08f8ed62398cfce7945c465c8998133f8e2c52
+F src/select.c 51e8b778abdd89289e2f2a6733d5e7ac6082f6c56ca717fa15f64f202e66bf42
 F src/shell.c.in ecff6f4ab0e8e25acd578b3eb27ac0bad4d48643c160259a277151d6e9d412e1
 F src/sqlite.h.in 2a35f62185eb5e7ecc64a2f68442b538ce9be74f80f28a00abc24837edcf1c17
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1950,8 +1950,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b6b9e185f8c44b5f2f51111f7c5e4e2d77c8b853c5be271467ce138e8066340c
-R 71f32b965c53fefec5ed2ab5db6eaed7
+P ba04142e09bb1ccc86824760a2e11df47e070285a2d09c2f61b75255886597cd
+R 10336f90bf1e8bd2097eb8ad35da3707
 U drh
-Z dfb5b3729b0976a766bdc021ea7b2468
+Z 3ded7fd2b5106a18a37cbebcaf60418c
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index cc8ec6cc3a3f59055834ed64e6d29fc253437e12..6ed0124f95b4195bfb4b45d4b95de995c94a0883 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-ba04142e09bb1ccc86824760a2e11df47e070285a2d09c2f61b75255886597cd
\ No newline at end of file
+cd8272fc2a34d1b245fd95208b9b601266ee7d2ff0f5ce52d03752f2c4e852a2
\ No newline at end of file

diff --git a/src/expr.c b/src/expr.c
index eb3ba35ba197059356e6feb3466bc14719f5f276..a300971345f8f288db43694ff71b25700d636e5e 100644 (file)
--- a/src/expr.c
+++ b/src/expr.c
@@ -1631,6 +1631,7 @@ ExprList *sqlite3ExprListDup(sqlite3 *db, const ExprList *p, int flags){
     pItem->eEName = pOldItem->eEName;
     pItem->done = 0;
     pItem->bNulls = pOldItem->bNulls;
+    pItem->bUsed = pOldItem->bUsed;
     pItem->bSorterRef = pOldItem->bSorterRef;
     pItem->u = pOldItem->u;
   }

diff --git a/src/resolve.c b/src/resolve.c
index 446004bfe254aaa7aea4f7978bfce40978378009..e9cfe9d9f1f3024e811bbb72ade9bf4d3ae261c2 100644 (file)
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -265,6 +265,7 @@ static int lookupName(
 
   assert( pNC );     /* the name context cannot be NULL. */
   assert( zCol );    /* The Z in X.Y.Z cannot be NULL */
+  assert( zDb==0 || zTab!=0 );
   assert( !ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced) );
 
   /* Initialize the node to no-match */
@@ -327,47 +328,50 @@ static int lookupName(
           assert( pEList!=0 );
           assert( pEList->nExpr==pTab->nCol );
           for(j=0; j<pEList->nExpr; j++){
-            if( sqlite3MatchEName(&pEList->a[j], zCol, zTab, zDb) ){
-              if( cnt>0 ){
-                if( pItem->fg.isUsing==0
-                 || sqlite3IdListIndex(pItem->u3.pUsing, zCol)<0
-                ){
-                  /* Two or more tables have the same column name which is
-                  ** not joined by USING.  This is an error.  Signal as much
-                  ** by clearing pFJMatch and letting cnt go above 1. */
-                  sqlite3ExprListDelete(db, pFJMatch);
-                  pFJMatch = 0;
-                }else
-                if( (pItem->fg.jointype & JT_RIGHT)==0 ){
-                  /* An INNER or LEFT JOIN.  Use the left-most table */
-                  continue;
-                }else
-                if( (pItem->fg.jointype & JT_LEFT)==0 ){
-                  /* A RIGHT JOIN.  Use the right-most table */
-                  cnt = 0;
-                  sqlite3ExprListDelete(db, pFJMatch);
-                  pFJMatch = 0;
-                }else{
-                  /* For a FULL JOIN, we must construct a coalesce() func */
-                  extendFJMatch(pParse, &pFJMatch, pMatch, pExpr->iColumn);
-                }
+            if( !sqlite3MatchEName(&pEList->a[j], zCol, zTab, zDb) ){
+              continue;
+            }
+            if( cnt>0 ){
+              if( pItem->fg.isUsing==0
+               || sqlite3IdListIndex(pItem->u3.pUsing, zCol)<0
+              ){
+                /* Two or more tables have the same column name which is
+                ** not joined by USING.  This is an error.  Signal as much
+                ** by clearing pFJMatch and letting cnt go above 1. */
+                sqlite3ExprListDelete(db, pFJMatch);
+                pFJMatch = 0;
+              }else
+              if( (pItem->fg.jointype & JT_RIGHT)==0 ){
+                /* An INNER or LEFT JOIN.  Use the left-most table */
+                continue;
+              }else
+              if( (pItem->fg.jointype & JT_LEFT)==0 ){
+                /* A RIGHT JOIN.  Use the right-most table */
+                cnt = 0;
+                sqlite3ExprListDelete(db, pFJMatch);
+                pFJMatch = 0;
+              }else{
+                /* For a FULL JOIN, we must construct a coalesce() func */
+                extendFJMatch(pParse, &pFJMatch, pMatch, pExpr->iColumn);
               }
-              cnt++;
-              cntTab = 2;
-              pMatch = pItem;
-              pExpr->iColumn = j;
-              hit = 1;
-              pEList->a[j].bUsed = 1;
             }
+            cnt++;
+            cntTab = 2;
+            pMatch = pItem;
+            pExpr->iColumn = j;
+            pEList->a[j].bUsed = 1;
+            hit = 1;
           }
           if( hit || zTab==0 ) continue;
         }
-        if( zDb ){
-          if( pTab->pSchema!=pSchema ) continue;
-          if( pSchema==0 && strcmp(zDb,"*")!=0 ) continue;
-        }
+        assert( zDb==0 || zTab!=0 );
         if( zTab ){
-          const char *zTabName = pItem->zAlias ? pItem->zAlias : pTab->zName;
+          const char *zTabName;
+          if( zDb ){
+            if( pTab->pSchema!=pSchema ) continue;
+            if( pSchema==0 && strcmp(zDb,"*")!=0 ) continue;
+          }
+          zTabName = pItem->zAlias ? pItem->zAlias : pTab->zName;
           assert( zTabName!=0 );
           if( sqlite3StrICmp(zTabName, zTab)!=0 ){
             continue;
@@ -410,6 +414,9 @@ static int lookupName(
             pMatch = pItem;
             /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
             pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
+            if( pItem->fg.isNestedFrom ){
+              sqlite3SrcItemColumnUsed(pItem, j);
+            }
             break;
           }
         }

diff --git a/src/select.c b/src/select.c
index d1605a565c85a90b2e23d598041279db45327be8..f0a3e5877582a89de24d92fd4bd08db4d4db93ce 100644 (file)
--- a/src/select.c
+++ b/src/select.c
@@ -2179,12 +2179,13 @@ int sqlite3ColumnsFromExprList(
   *paCol = aCol;
 
   for(i=0, pCol=aCol; i<nCol && !db->mallocFailed; i++, pCol++){
+    struct ExprList_item *pX = &pEList->a[i];
     /* Get an appropriate name for the column
     */
-    if( (zName = pEList->a[i].zEName)!=0 && pEList->a[i].eEName==ENAME_NAME ){
+    if( (zName = pX->zEName)!=0 && pX->eEName==ENAME_NAME ){
       /* If the column contains an "AS <name>" phrase, use <name> as the name */
     }else{
-      Expr *pColExpr = sqlite3ExprSkipCollateAndLikely(pEList->a[i].pExpr);
+      Expr *pColExpr = sqlite3ExprSkipCollateAndLikely(pX->pExpr);
       while( ALWAYS(pColExpr!=0) && pColExpr->op==TK_DOT ){
         pColExpr = pColExpr->pRight;
         assert( pColExpr!=0 );
@@ -2202,7 +2203,7 @@ int sqlite3ColumnsFromExprList(
         zName = pColExpr->u.zToken;
       }else{
         /* Use the original text of the column expression as its name */
-        zName = pEList->a[i].zEName;
+        assert( zName==pX->zEName );  /* pointer comparison intended */
       }
     }
     if( zName && !sqlite3IsTrueOrFalse(zName) ){
@@ -5827,9 +5828,7 @@ static int selectExpander(Walker *pWalker, Select *p){
           }
           for(j=0; j<pTab->nCol; j++){
             char *zName = pTab->aCol[j].zCnName;
-            char *zColname;  /* The computed column name */
-            char *zToFree;   /* Malloced string that needs to be freed */
-            Token sColname;  /* Computed column name as a token */
+            struct ExprList_item *pX; /* Newly added ExprList term */
 
             assert( zName );
             if( zTName && pSub
@@ -5859,13 +5858,6 @@ static int selectExpander(Walker *pWalker, Select *p){
               }
             }
             pRight = sqlite3Expr(db, TK_ID, zName);
-            if( longNames ){
-              zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
-              zToFree = zColname;
-            }else{
-              zColname = zName;
-              zToFree = 0;
-            }
             if( (pTabList->nSrc>1
                  && (  (pFrom->fg.jointype & JT_LTORJ)==0
                      || !inAnyUsingClause(zName,pFrom,pTabList->nSrc-i-1)
@@ -5887,23 +5879,28 @@ static int selectExpander(Walker *pWalker, Select *p){
               pExpr = pRight;
             }
             pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
-
-            sqlite3TokenInit(&sColname, zColname);
-            sqlite3ExprListSetName(pParse, pNew, &sColname, 0);
-            if( pNew && (p->selFlags & SF_NestedFrom)!=0 && !IN_RENAME_OBJECT ){
-              struct ExprList_item *pX = &pNew->a[pNew->nExpr-1];
-              sqlite3DbFree(db, pX->zEName);
+            if( pNew==0 ){
+              break;  /* OOM */
+            }
+            pX = &pNew->a[pNew->nExpr-1];
+            assert( pX->zEName==0 );
+            if( (selFlags & SF_NestedFrom)!=0 && !IN_RENAME_OBJECT ){
               if( pSub ){
                 pX->zEName = sqlite3DbStrDup(db, pSub->pEList->a[j].zEName);
                 testcase( pX->zEName==0 );
               }else{
                 pX->zEName = sqlite3MPrintf(db, "%s.%s.%s",
-                                           zSchemaName, zTabName, zColname);
+                                           zSchemaName, zTabName, zName);
                 testcase( pX->zEName==0 );
               }
               pX->eEName = ENAME_TAB;
+            }else if( longNames ){
+              pX->zEName = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
+              pX->eEName = ENAME_NAME;
+            }else{
+              pX->zEName = sqlite3DbStrDup(db, zName);
+              pX->eEName = ENAME_NAME;
             }
-            sqlite3DbFree(db, zToFree);
           }
         }
         if( !tableSeen ){
@@ -7029,6 +7026,18 @@ int sqlite3Select(
   */
   if( pDest->eDest==SRT_EphemTab ){
     sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr);
+    if( p->selFlags & SF_NestedFrom ){
+      /* Delete or NULL-out result columns that will never be used */
+      int ii;
+      for(ii=pEList->nExpr-1; ii>0 && pEList->a[ii].bUsed==0; ii--){
+        sqlite3ExprDelete(db, pEList->a[ii].pExpr);
+        sqlite3DbFree(db, pEList->a[ii].zEName);
+        pEList->nExpr--;
+      }
+      for(ii=0; ii<pEList->nExpr; ii++){
+        if( pEList->a[ii].bUsed==0 ) pEList->a[ii].pExpr->op = TK_NULL;
+      }
+    }
   }
 
   /* Set the limiter.