From: drh <>
Date: Mon, 24 Oct 2022 21:58:51 +0000 (+0000)
Subject: This check-in attempts to make the SrcItem object smaller by combining the
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fheads%2Ffailed-opt-attempt;p=thirdparty%2Fsqlite.git

This check-in attempts to make the SrcItem object smaller by combining the
zDatabase and pSchema fields into a single union.  It mostly works, but there
are some issues, and the performance savings is minimal.  So it is side-tracked
onto this dead-end branch.

FossilOrigin-Name: 80fbb30f28c8a468d71a367968bb0c4b17cbc8080dff333a359fea09e9907550
---

diff --git a/manifest b/manifest
index bf748e6b59..be42a01451 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\stypo\sin\scomment.
-D 2022-10-24T18:42:45.118
+C This\scheck-in\sattempts\sto\smake\sthe\sSrcItem\sobject\ssmaller\sby\scombining\sthe\nzDatabase\sand\spSchema\sfields\sinto\sa\ssingle\sunion.\s\sIt\smostly\sworks,\sbut\sthere\nare\ssome\sissues,\sand\sthe\sperformance\ssavings\sis\sminimal.\s\sSo\sit\sis\sside-tracked\nonto\sthis\sdead-end\sbranch.
+D 2022-10-24T21:58:51.621
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -554,7 +554,7 @@ F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F sqlite_cfg.h.in baf2e409c63d4e7a765e17769b6ff17c5a82bbd9cbf1e284fd2e4cefaff3fcf2
 F src/alter.c 0390ca1d69ec3626cfa9f153114b7ab233e6b2bada6a9eb91361ed385fe90deb
 F src/analyze.c d2fce73f6a024897593012c6ca25368629fa4aeb49960d88a52fac664582e483
-F src/attach.c 4431f82f0247bf3aaf91589acafdff77d1882235c95407b36da1585c765fbbc8
+F src/attach.c a00838bc34e10cd4e4ff889b452097fc2c6cbbec5f3a9c2519220fbfb9eb1ef6
 F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
@@ -562,15 +562,15 @@ F src/btmutex.c 6ffb0a22c19e2f9110be0964d0731d2ef1c67b5f7fabfbaeb7b9dabc4b7740ca
 F src/btree.c 74fc5f6a0577df703d6f98d0c51ee0d8d91d22dbc0ba86e42e056517e2b45576
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
 F src/btreeInt.h 8ce1332edd89dfd2461d561ac10a0ab5601c8e06200cb5230596c3caaf54482e
-F src/build.c d3e43e950e4e377c1d451a4862556792acdef1faba14a03f899d30d09731c48b
+F src/build.c 532fa3bebc352fb6853425e5955a9bd29eeb9d5e8e226a68b4a9d3cfed4e9207
 F src/callback.c 4cd7225b26a97f7de5fee5ae10464bed5a78f2adefe19534cc2095b3a8ca484a
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 20507cc0b0a6c19cd882fcd0eaeda32ae6a4229fb4b024cfdf3183043d9b703d
 F src/date.c 94ce83b4cd848a387680a5f920c9018c16655db778c4d36525af0a0f34679ac5
 F src/dbpage.c 5808e91bc27fa3981b028000f8fadfdc10ce9e59a34ce7dc4e035a69be3906ec
 F src/dbstat.c 861e08690fcb0f2ee1165eff0060ea8d4f3e2ea10f80dab7d32ad70443a6ff2d
-F src/delete.c 86573edae75e3d3e9a8b590d87db8e47222103029df4f3e11fa56044459b514e
-F src/expr.c 847f87d9df3ede2b2b0a8db088af0b9c1923b21009f8ea1b9b7b28cb0a383170
+F src/delete.c 9b57791bc6f0a8efb4e31ebbf8a4fb8ed0c4e534bc0010d61e2fe77a6ee24114
+F src/expr.c f48f0535844b0126e4e0f480da790cc2d4230eae5acdf4bf42a853aa66b78961
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 722f20779f5342a787922deded3628d8c74b5249cab04098cf17ee2f2aaff002
 F src/func.c fe2a795ad647ce42054873ac91c43beb7b5d204892903a67f6e7e314379b9d4a
@@ -609,23 +609,23 @@ F src/os_win.c 8d129ae3e59e0fa900e20d0ad789e96f2e08177f0b00b53cdda65c40331e0902
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 6176d9752eb580419e8fef4592dc417a6b00ddfd43ee22f818819bf8840ceee8
 F src/pager.h f82e9844166e1585f5786837ddc7709966138ced17f568c16af7ccf946c2baa3
-F src/parse.y 8e67d820030d2655b9942ffe61c1e7e6b96cea2f2f72183533299393907d0564
+F src/parse.y c9f1b67e76a042b8d50e299d061b74d3f7a74f262c378dc80ceea184b376fdb0
 F src/pcache.c f4268f7f73c6a3db12ce22fd25bc68dc42315d19599414ab1207d7cf32f79197
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c dee95e3cd2b61e6512dc814c5ab76d5eb36f0bfc9441dbb4260fccc0d12bbddc
 F src/pragma.c 41430ca04735cc8e5d003bfd9315eadede3ec326e50805cc81bcf34e46601292
 F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c 1b02be0441eda4579471fea097f678effcbb77ef0c39ab3f703c837822bcd674
-F src/printf.c e99ee9741e79ae3873458146f59644276657340385ade4e76a5f5d1c25793764
+F src/printf.c 615d24684bee3c3217070b19865ab6b9f4f346fb5fc0b92bddc54d45050e5634
 F src/random.c 546d6feb15ec69c1aafe9bb351a277cbb498fd5410e646add673acb805714960
 F src/resolve.c efea4e5fbecfd6d0a9071b0be0d952620991673391b6ffaaf4c277b0bb674633
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c e5b6f930f068c9c5362fc76c704ae5cb5ef1e3f18759c2126f23b0cf04c0e263
+F src/select.c 90883c8b0d8bfc6623a77d24d7f822f0c50545f02860634d962ae09b3ea525e3
 F src/shell.c.in 97f4ee3966d7d8ffcd976658ea3b92bc9a670eb988d2e8aeb2243789631689a6
 F src/sqlite.h.in d9c8a6243fc0a1c270d69db33758e34b810af3462f9bc5b4af113b347e07c69d
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 5336beea1868d99d2f62e628dbea55e97267dbff8193291ab175e960c5df9141
-F src/sqliteInt.h 9a40d5b075cd2e78bac6f9ae724e3fa4281373cb728f961272cb182f6ba94ce6
+F src/sqliteInt.h b12ab310eefa22ec23af050ff163cf5e0332404583f0252f5843132b9a25c1c2
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -686,7 +686,7 @@ F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
 F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
 F src/tokenize.c 1305797eab3542a0896b552c6e7669c972c1468e11e92b370533c1f37a37082b
 F src/treeview.c 07787f67cd297a6d09d04b8d70c06769c60c9c1d9080378f93929c16f8fd3298
-F src/trigger.c 4163ada044af89d51caba1cb713a73165347b2ec05fe84a283737c134d61fcd5
+F src/trigger.c 70431e371037390ca45d373a3b1b87f427f3883a352a42051f427e44fc9a5e9a
 F src/update.c 5b0302c47cf31b533d5dff04c497ca1d8b9d89c39727e633fbe7b882fd5ac5aa
 F src/upsert.c 5303dc6c518fa7d4b280ec65170f465c7a70b7ac2b22491598f6d0b4875b3145
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
@@ -2037,8 +2037,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 69d704224e9ed022fcec591beff2ffcc4daf3e7fc586debfdcf00b25c1fddd87
-R e2a88fcf6a9d4446fa629ea861bc8ca4
+P f65c95658fe4d30817da8de7eb88e823ea1cd8be40e347d626870bad3cc13359
+R bd44daf142420861734ecc490ea27084
+T *branch * failed-opt-attempt
+T *sym-failed-opt-attempt *
+T -sym-trunk *
 U drh
-Z ea85a8ca90f8837e6e02f1969966b7f9
+Z 625f2743307b64b5e1b75f4704026ffe
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index c85389d8a2..d496849841 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-f65c95658fe4d30817da8de7eb88e823ea1cd8be40e347d626870bad3cc13359
\ No newline at end of file
+80fbb30f28c8a468d71a367968bb0c4b17cbc8080dff333a359fea09e9907550
\ No newline at end of file
diff --git a/src/attach.c b/src/attach.c
index 1732be27bf..2023d00ea6 100644
--- a/src/attach.c
+++ b/src/attach.c
@@ -465,19 +465,20 @@ static int fixSelectCb(Walker *p, Select *pSelect){
   if( NEVER(pList==0) ) return WRC_Continue;
   for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
     if( pFix->bTemp==0 ){
-      if( pItem->zDatabase ){
-        if( iDb!=sqlite3FindDbName(db, pItem->zDatabase) ){
+      if( pItem->fg.useSchema==0 && pItem->u4.zDatabase!=0 ){
+        if( iDb!=sqlite3FindDbName(db, pItem->u4.zDatabase) ){
           sqlite3ErrorMsg(pFix->pParse,
               "%s %T cannot reference objects in database %s",
-              pFix->zType, pFix->pName, pItem->zDatabase);
+              pFix->zType, pFix->pName, pItem->u4.zDatabase);
           return WRC_Abort;
         }
-        sqlite3DbFree(db, pItem->zDatabase);
-        pItem->zDatabase = 0;
+        sqlite3DbFree(db, pItem->u4.zDatabase);
+        pItem->u4.zDatabase = 0;
         pItem->fg.notCte = 1;
       }
-      pItem->pSchema = pFix->pSchema;
+      pItem->fg.useSchema = 1;
       pItem->fg.fromDDL = 1;
+      pItem->u4.pSchema = pFix->pSchema;
     }
 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
     if( pList->a[i].fg.isUsing==0
diff --git a/src/build.c b/src/build.c
index effaeb7332..6ae07221f8 100644
--- a/src/build.c
+++ b/src/build.c
@@ -499,12 +499,11 @@ Table *sqlite3LocateTableItem(
   SrcItem *p
 ){
   const char *zDb;
-  assert( p->pSchema==0 || p->zDatabase==0 );
-  if( p->pSchema ){
-    int iDb = sqlite3SchemaToIndex(pParse->db, p->pSchema);
+  if( p->fg.useSchema ){
+    int iDb = sqlite3SchemaToIndex(pParse->db, p->u4.pSchema);
     zDb = pParse->db->aDb[iDb].zDbSName;
   }else{
-    zDb = p->zDatabase;
+    zDb = p->u4.zDatabase;
   }
   return sqlite3LocateTable(pParse, flags, p->zName, zDb);
 }
@@ -3474,7 +3473,8 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
 
   if( pTab==0 ){
     if( noErr ){
-      sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].zDatabase);
+      assert( pName->a[0].fg.useSchema==0 );
+      sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].u4.zDatabase);
       sqlite3ForceNotReadOnly(pParse);
     }
     goto exit_drop_table;
@@ -4568,12 +4568,13 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
   if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
     goto exit_drop_index;
   }
-  pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
+  assert( pName->a[0].fg.useSchema==0 );
+  pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].u4.zDatabase);
   if( pIndex==0 ){
     if( !ifExists ){
       sqlite3ErrorMsg(pParse, "no such index: %S", pName->a);
     }else{
-      sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].zDatabase);
+      sqlite3CodeVerifyNamedSchema(pParse, pName->a[0].u4.zDatabase);
       sqlite3ForceNotReadOnly(pParse);
     }
     pParse->checkSchema = 1;
@@ -4818,7 +4819,7 @@ SrcList *sqlite3SrcListEnlarge(
 ** points to the table name and the pTable points to the database name.
 ** The SrcList.a[].zName field is filled with the table name which might
 ** come from pTable (if pDatabase is NULL) or from pDatabase.  
-** SrcList.a[].zDatabase is filled with the database name from pTable,
+** SrcList.a[].u4.zDatabase is filled with the database name from pTable,
 ** or with NULL if no database is specified.
 **
 ** In other words, if call like this:
@@ -4870,12 +4871,13 @@ SrcList *sqlite3SrcListAppend(
   if( pDatabase && pDatabase->z==0 ){
     pDatabase = 0;
   }
+  assert( pItem->fg.useSchema==0 );
   if( pDatabase ){
     pItem->zName = sqlite3NameFromToken(db, pDatabase);
-    pItem->zDatabase = sqlite3NameFromToken(db, pTable);
+    pItem->u4.zDatabase = sqlite3NameFromToken(db, pTable);
   }else{
     pItem->zName = sqlite3NameFromToken(db, pTable);
-    pItem->zDatabase = 0;
+    pItem->u4.zDatabase = 0;
   }
   return pList;
 }
@@ -4907,9 +4909,11 @@ void sqlite3SrcListDelete(sqlite3 *db, SrcList *pList){
   assert( db!=0 );
   if( pList==0 ) return;
   for(pItem=pList->a, i=0; i<pList->nSrc; i++, pItem++){
-    if( pItem->zDatabase ) sqlite3DbNNFreeNN(db, pItem->zDatabase);
     if( pItem->zName ) sqlite3DbNNFreeNN(db, pItem->zName);
     if( pItem->zAlias ) sqlite3DbNNFreeNN(db, pItem->zAlias);
+    if( pItem->fg.useSchema==0 && pItem->u4.zDatabase ){
+      sqlite3DbNNFreeNN(db, pItem->u4.zDatabase);
+    }
     if( pItem->fg.isIndexedBy ) sqlite3DbFree(db, pItem->u1.zIndexedBy);
     if( pItem->fg.isTabFunc ) sqlite3ExprListDelete(db, pItem->u1.pFuncArg);
     sqlite3DeleteTable(db, pItem->pTab);
diff --git a/src/delete.c b/src/delete.c
index 704a3c7110..55379b02a0 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -153,7 +153,8 @@ void sqlite3MaterializeView(
   if( pFrom ){
     assert( pFrom->nSrc==1 );
     pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
-    pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
+    assert( pFrom->a[0].fg.useSchema==0 );
+    pFrom->a[0].u4.zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
     assert( pFrom->a[0].fg.isUsing==0 );
     assert( pFrom->a[0].u3.pOn==0 );
   }
diff --git a/src/expr.c b/src/expr.c
index 7a4e59f28d..ff74f307b8 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1664,8 +1664,11 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, const SrcList *p, int flags){
     SrcItem *pNewItem = &pNew->a[i];
     const SrcItem *pOldItem = &p->a[i];
     Table *pTab;
-    pNewItem->pSchema = pOldItem->pSchema;
-    pNewItem->zDatabase = sqlite3DbStrDup(db, pOldItem->zDatabase);
+    if( pOldItem->fg.useSchema ){
+      pNewItem->u4.pSchema = pOldItem->u4.pSchema;
+    }else{
+      pNewItem->u4.zDatabase = sqlite3DbStrDup(db, pOldItem->u4.zDatabase);
+    }
     pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
     pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);
     pNewItem->fg = pOldItem->fg;
diff --git a/src/parse.y b/src/parse.y
index d627f22ba2..084d9a960b 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -719,7 +719,9 @@ seltablist(A) ::= stl_prefix(A) nm(Y) dbnm(D) LP exprlist(E) RP as(Z) on_using(N
         SrcItem *pNew = &A->a[A->nSrc-1];
         SrcItem *pOld = F->a;
         pNew->zName = pOld->zName;
-        pNew->zDatabase = pOld->zDatabase;
+        assert( pOld->fg.useSchema==0 );
+        assert( pNew->fg.useSchema==0 );
+        pNew->u4.zDatabase = pOld->u4.zDatabase;
         pNew->pSelect = pOld->pSelect;
         if( pNew->pSelect && (pNew->pSelect->selFlags & SF_NestedFrom)!=0 ){
           pNew->fg.isNestedFrom = 1;
@@ -730,7 +732,7 @@ seltablist(A) ::= stl_prefix(A) nm(Y) dbnm(D) LP exprlist(E) RP as(Z) on_using(N
           pOld->fg.isTabFunc = 0;
           pNew->fg.isTabFunc = 1;
         }
-        pOld->zName = pOld->zDatabase = 0;
+        pOld->zName = pOld->u4.zDatabase = 0;
         pOld->pSelect = 0;
       }
       sqlite3SrcListDelete(pParse->db, F);
diff --git a/src/printf.c b/src/printf.c
index 3602e1fcb9..180b4f7cef 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -877,8 +877,8 @@ void sqlite3_str_vappendf(
         if( pItem->zAlias && !flag_altform2 ){
           sqlite3_str_appendall(pAccum, pItem->zAlias);
         }else if( pItem->zName ){
-          if( pItem->zDatabase ){
-            sqlite3_str_appendall(pAccum, pItem->zDatabase);
+          if( pItem->fg.useSchema==0 && pItem->u4.zDatabase!=0 ){
+            sqlite3_str_appendall(pAccum, pItem->u4.zDatabase);
             sqlite3_str_append(pAccum, ".", 1);
           }
           sqlite3_str_appendall(pAccum, pItem->zName);
diff --git a/src/select.c b/src/select.c
index 42a476c00f..2d184fe04a 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4386,10 +4386,12 @@ static int flattenSubquery(
 
   /* Delete the transient structures associated with thesubquery */
   pSub1 = pSubitem->pSelect;
-  sqlite3DbFree(db, pSubitem->zDatabase);
+  if( pSubitem->fg.useSchema==0 && pSubitem->u4.zDatabase ){
+    sqlite3DbFree(db, pSubitem->u4.zDatabase);
+    pSubitem->u4.zDatabase = 0;
+  }
   sqlite3DbFree(db, pSubitem->zName);
   sqlite3DbFree(db, pSubitem->zAlias);
-  pSubitem->zDatabase = 0;
   pSubitem->zName = 0;
   pSubitem->zAlias = 0;
   pSubitem->pSelect = 0;
@@ -5347,7 +5349,8 @@ static struct Cte *searchWith(
 ){
   const char *zName = pItem->zName;
   With *p;
-  assert( pItem->zDatabase==0 );
+  assert( pItem->fg.useSchema==0 );
+  assert( pItem->u4.zDatabase==0 );
   assert( zName!=0 );
   for(p=pWith; p; p=p->pOuter){
     int i;
@@ -5428,7 +5431,7 @@ static int resolveFromTermToCte(
     ** go no further. */
     return 0;
   }
-  if( pFrom->zDatabase!=0 ){
+  if( pFrom->fg.useSchema || pFrom->u4.zDatabase!=0 ){
     /* The FROM term contains a schema qualifier (ex: main.t1) and so
     ** it cannot possibly be a CTE reference. */
     return 0;
@@ -5508,7 +5511,8 @@ static int resolveFromTermToCte(
       assert( pRecTerm->pPrior!=0 );
       for(i=0; i<pSrc->nSrc; i++){
         SrcItem *pItem = &pSrc->a[i];
-        if( pItem->zDatabase==0 
+        if( pItem->fg.useSchema==0
+         && pItem->u4.zDatabase==0 
          && pItem->zName!=0 
          && 0==sqlite3StrICmp(pItem->zName, pCte->zName)
         ){
@@ -6940,7 +6944,8 @@ int sqlite3Select(
     ** string for the fake column name seems safer.
     */
     if( pItem->colUsed==0 && pItem->zName!=0 ){
-      sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, "", pItem->zDatabase);
+      sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, "",
+                       pItem->fg.useSchema ? "" : pItem->u4.zDatabase);
     }
 
 #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 3dde0f6f9c..05a1674198 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3110,8 +3110,6 @@ struct IdList {
 **    u2.pCteUse             fg.isCte       && !fg.isIndexedBy
 */
 struct SrcItem {
-  Schema *pSchema;  /* Schema to which this item is fixed */
-  char *zDatabase;  /* Name of database holding this table */
   char *zName;      /* Name of the table */
   char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
   Table *pTab;      /* An SQL table corresponding to zName */
@@ -3135,8 +3133,13 @@ struct SrcItem {
     unsigned isOn :1;          /* u3.pOn was once valid and non-NULL */
     unsigned isSynthUsing :1;  /* u3.pUsing is synthensized from NATURAL */
     unsigned isNestedFrom :1;  /* pSelect is a SF_NestedFrom subquery */
+    unsigned useSchema :1;     /* use u4.pSchema rather than u4.zDatabase */
   } fg;
   int iCursor;      /* The VDBE cursor number used to access this table */
+  union {
+    Schema *pSchema;  /* Schema to which this item is fixed */
+    char *zDatabase;  /* Name of database holding this table */
+  } u4;
   union {
     Expr *pOn;        /* fg.isUsing==0 =>  The ON clause of a join */
     IdList *pUsing;   /* fg.isUsing==1 =>  The USING clause of a join */
diff --git a/src/trigger.c b/src/trigger.c
index ca64d6145b..86ba79bf26 100644
--- a/src/trigger.c
+++ b/src/trigger.c
@@ -152,8 +152,9 @@ void sqlite3BeginTrigger(
   ** name on pTableName if we are reparsing out of the schema table
   */
   if( db->init.busy && iDb!=1 ){
-    sqlite3DbFree(db, pTableName->a[0].zDatabase);
-    pTableName->a[0].zDatabase = 0;
+    assert( pTableName->a[0].fg.useSchema==0 );
+    sqlite3DbFree(db, pTableName->a[0].u4.zDatabase);
+    pTableName->a[0].u4.zDatabase = 0;
   }
 
   /* If the trigger name was unqualified, and the table is a temp table,
@@ -626,7 +627,8 @@ void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
   }
 
   assert( pName->nSrc==1 );
-  zDb = pName->a[0].zDatabase;
+  assert( pName->a[0].fg.useSchema==0 );
+  zDb = pName->a[0].u4.zDatabase;
   zName = pName->a[0].zName;
   assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
   for(i=OMIT_TEMPDB; i<db->nDb; i++){
@@ -863,7 +865,8 @@ SrcList *sqlite3TriggerStepSrc(
     Schema *pSchema = pStep->pTrig->pSchema;
     pSrc->a[0].zName = zName;
     if( pSchema!=db->aDb[1].pSchema ){
-      pSrc->a[0].pSchema = pSchema;
+      pSrc->a[0].fg.useSchema = 1;
+      pSrc->a[0].u4.pSchema = pSchema;
     }
     if( pStep->pFrom ){
       SrcList *pDup = sqlite3SrcListDup(db, pStep->pFrom, 0);