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

1 files changed, 42 insertions, 35 deletions

diff --git a/src/resolve.c b/src/resolve.c
index 446004bfe..e9cfe9d9f 100644
--- 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;
           }
         }