From: drh <>
Date: Wed, 20 Apr 2022 21:58:32 +0000 (+0000)
Subject: Try to avoid materializing unused columns when processing a
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fe483fd10bfc07b88238c955ec72c4418b972f84;p=thirdparty%2Fsqlite.git

Try to avoid materializing unused columns when processing a
parenthesized FROM clause.

FossilOrigin-Name: 07906e3c4fcefa721a1dfd57590778cf9c278e93b1f86128843c743d6aca7106
---

diff --git a/manifest b/manifest
index cc8af505d8..340ecc4211 100644
--- 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 Try\sto\savoid\smaterializing\sunused\scolumns\swhen\sprocessing\sa\nparenthesized\sFROM\sclause.
+D 2022-04-20T21:58:32.066
 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 05cc45c50c07dcf42c1ef1d699a297e47e3a20d3cd15a720ea1cf8084b92d067
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c 8978bab868e63781d91d0b689b08f8ed62398cfce7945c465c8998133f8e2c52
+F src/select.c 4b10a6b722049aed1c6c484487d8929fb751795032abfd839eeabd868572d24c
 F src/shell.c.in ecff6f4ab0e8e25acd578b3eb27ac0bad4d48643c160259a277151d6e9d412e1
 F src/sqlite.h.in 2a35f62185eb5e7ecc64a2f68442b538ce9be74f80f28a00abc24837edcf1c17
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1950,8 +1950,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b6b9e185f8c44b5f2f51111f7c5e4e2d77c8b853c5be271467ce138e8066340c
-R 71f32b965c53fefec5ed2ab5db6eaed7
+P ba04142e09bb1ccc86824760a2e11df47e070285a2d09c2f61b75255886597cd
+R b23b598bef12799a965bda79b8cd53ae
+T *branch * right-join-paren
+T *sym-right-join-paren *
+T -sym-right-join *
 U drh
-Z dfb5b3729b0976a766bdc021ea7b2468
+Z f15a93d7fb29359c0ceb7d324d13be94
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index cc8ec6cc3a..76c96970e9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-ba04142e09bb1ccc86824760a2e11df47e070285a2d09c2f61b75255886597cd
\ No newline at end of file
+07906e3c4fcefa721a1dfd57590778cf9c278e93b1f86128843c743d6aca7106
\ No newline at end of file
diff --git a/src/expr.c b/src/expr.c
index eb3ba35ba1..a300971345 100644
--- 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 446004bfe2..bbd28a5b03 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 */
@@ -362,12 +363,14 @@ static int lookupName(
           }
           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 +413,9 @@ 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 d1605a565c..d8c7a90649 100644
--- a/src/select.c
+++ b/src/select.c
@@ -7029,6 +7029,18 @@ 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.