When doing a multi-drop, delete btrees beginning with the largest root page

first and working toward smaller root pages, to avoid problems with root page
renumbering due to autovacuum.

FossilOrigin-Name: 37d4c5e207888b49c224275b05abfc1f63a2d8d2133bcc8970188b15387926ef

diff --git a/manifest b/manifest
index 84a66be780b98aeb4a55ce39f1c6c2546c4479e4..f8caa0c4815ea04a0f2e207d42200e1fe39adbd8 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Attempt\sto\sfix\smulti-object\sDROP.\s\sWorking\sbetter,\sbut\sstill\snot\sperfect.
-D 2024-02-29T19:40:38.822
+C When\sdoing\sa\smulti-drop,\sdelete\sbtrees\sbeginning\swith\sthe\slargest\sroot\spage\nfirst\sand\sworking\stoward\ssmaller\sroot\spages,\sto\savoid\sproblems\swith\sroot\spage\nrenumbering\sdue\sto\sautovacuum.
+D 2024-03-01T12:21:45.438
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -692,7 +692,7 @@ F src/btmutex.c 79a43670447eacc651519a429f6ece9fd638563cf95b469d6891185ddae2b522
 F src/btree.c 285b493d843e7ba8ef78b6ae7d31238e904901dbc0c484f7904de4cf18fd8802
 F src/btree.h 55066f513eb095db935169dab1dc2f7c7a747ef223c533f5d4ad4dfed346cbd0
 F src/btreeInt.h 98aadb6dcb77b012cab2574d6a728fad56b337fc946839b9898c4b4c969e30b6
-F src/build.c 25384963d1b9d6ebc73777bc7c1112973ba36ea8a8ca9f0a39bd94c047ba24eb
+F src/build.c 39344791925e956a11ac74aca8d4ce3d34a5982e33a97bfea1b9a8ed8d5f995c
 F src/callback.c db3a45e376deff6a16c0058163fe0ae2b73a2945f3f408ca32cf74960b28d490
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 23331529e654be40ca97d171cbbffe9b3d4c71cc53b78fe5501230675952da8b
@@ -755,7 +755,7 @@ F src/shell.c.in 2ec564ed3ff0147036be313efeb47b3dbfb8753d5eb5ea0e90636427c6b3a36
 F src/sqlite.h.in 19a2db3995a699bd7f6dfb423856242bfceb7ec849a93c91d241d19fc28d9f0f
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 3f046c04ea3595d6bfda99b781926b17e672fd6d27da2ba6d8d8fc39981dcb54
-F src/sqliteInt.h bdb0bba047cd39c8733c14131c379a91f3d1f437c57f11270db14860ab09dffd
+F src/sqliteInt.h d5101433f13bd5944472c1b4c28a2eaa198c9773f8c54496b57095b27289bfe9
 F src/sqliteLimit.h 6878ab64bdeb8c24a1d762d45635e34b96da21132179023338c93f820eee6728
 F src/status.c cb11f8589a6912af2da3bb1ec509a94dd8ef27df4d4c1a97e0bcf2309ece972b
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -2177,8 +2177,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 2266086cf08ee710338667d1cf0b1e81ce7380101707db272ce27124404068a0
-R d3490d0df600a6062bf18828bf499fc3
+P 02f9fc73eef80f528097581580977aae46942baac2d7fb205c52f7f25472f2a8
+R 6e23b5efb65bccda72802397068f9d95
 U drh
-Z 68bbccadbf2f82f26c1558f6e4711d24
+Z f617c5603de9e2495d967184783943a7
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index 7cbde2128229e98218e92aa156a57e26c2a559cd..087e4f307dec3d2664f7f1f96b61015d5fe6dc64 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-02f9fc73eef80f528097581580977aae46942baac2d7fb205c52f7f25472f2a8
\ No newline at end of file
+37d4c5e207888b49c224275b05abfc1f63a2d8d2133bcc8970188b15387926ef
\ No newline at end of file

diff --git a/src/build.c b/src/build.c
index dbad6443044a6891abae0a991821e442475f3b0e..9b2d808fe7b5d8c91cac5b0bc02ec17b635cc4de 100644 (file)
--- a/src/build.c
+++ b/src/build.c
@@ -3479,7 +3479,7 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
   Table *pTab;
   sqlite3 *db = pParse->db;
   int iDb;
-  int ii;
+  int ii, jj;
 
   (void)sqlite3GetVdbe(pParse);
   sqlite3ReadSchema(pParse);
@@ -3575,40 +3575,41 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
     /* If this table or view has appeared previously in the list of tables
     ** or views to be dropped, then the prior appearance is sufficient so
     ** skip this one. */
-    if( ii>0 ){
-      int jj;
-      for(jj=0; jj<ii && pName->a[jj].pTab!=pTab; jj++){}
-      if( jj<ii ) continue;
-    }
+    for(jj=ii-1; jj>=0 && pName->a[jj].pTab!=pTab; jj--){}
+    if( jj>=0 ) continue;
 
     /* Remember the table for use in the second pass */
     pName->a[ii].pTab = pTab;
     pTab->nTabRef++;
-  }
+    pName->a[ii].regReturn = IsOrdinaryTable(pTab) ? pTab->tnum : 1;
 
-  for(ii=0; pParse->nErr==0 && ii<pName->nSrc; ii++){
-    pTab = pName->a[ii].pTab;
-    if( pTab ){
-      iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
-    
-      /* Generate code to clear this table from sqlite_statN and to
-      ** cascade foreign key constraints.
-      */
-      sqlite3BeginWriteOperation(pParse, 1, iDb);
-      if( IsOrdinaryTable(pTab) ){
-        sqlite3ClearStatTables(pParse, iDb, "tbl", pTab->zName);
-        sqlite3FkDropTable(pParse, &pName->a[ii], pTab);
+    /* Generate code to clear this table from sqlite_statN and to
+    ** cascade foreign key constraints.
+    */
+    sqlite3BeginWriteOperation(pParse, 1, iDb);
+    if( IsOrdinaryTable(pTab) ){
+      sqlite3ClearStatTables(pParse, iDb, "tbl", pTab->zName);
+      sqlite3FkDropTable(pParse, &pName->a[ii], pTab);
+    }
+  }
+
+  /* Generate code to actually delete the tables/views in a second pass. 
+  ** Btrees must be deleted largest root page first, to avoid problems
+  ** caused by autovacuum page reordering. */
+  while( pParse->nErr==0 ){
+    int iBest = 0;
+    for(ii=jj=0; ii<pName->nSrc; ii++){
+      if( pName->a[ii].regReturn<=0 ) continue;
+      if( pName->a[ii].regReturn>iBest ){
+        jj = ii;
+        iBest = pName->a[ii].regReturn;
       }
     }
-  }
-
-  /* Generate code to actually delete the tables/views in a second pass. */
-  for(ii=0; pParse->nErr==0 && ii<pName->nSrc; ii++){
-    pTab = pName->a[ii].pTab;
-    if( pTab ){
-      iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
-      sqlite3CodeDropTable(pParse, pTab, iDb, isView);
-    }
+    if( iBest==0 ) break;
+    pTab = pName->a[jj].pTab;
+    pName->a[jj].regReturn = 0;
+    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+    sqlite3CodeDropTable(pParse, pTab, iDb, isView);
   }
   sqlite3SrcListDelete(db, pName);
 }
@@ -4613,11 +4614,12 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
   sqlite3 *db = pParse->db;
   Vdbe *v;
   int iDb;
-  int ii;
+  int ii, jj;
 
   sqlite3ReadSchema(pParse);
   assert( pName!=0 || pParse->nErr!=0 );
   for(ii=0; pParse->nErr==0 && ii<pName->nSrc; ii++){
+    pName->a[ii].regReturn = 0;
     pIndex = sqlite3FindIndex(db, pName->a[ii].zName, pName->a[ii].zDatabase);
     if( pIndex==0 ){
       if( !ifExists ){
@@ -4660,19 +4662,17 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
 #endif
 
     /* Skip over redundant DROP INDEXes */
-    if( ii>0 ){
-      int jj;
-      for(jj=0; jj<ii; jj++){
-        if( pName->a[jj].addrFillSub!=iDb ) continue;
-        if( pName->a[jj].regReturn!=pIndex->tnum ) continue;
-        break;
-      }
-      if( jj<ii ) continue;
-    }
-    pName->a[ii].addrFillSub = iDb;
+    for(jj=ii-1; jj>=0 && pName->a[jj].u2.pIdx!=pIndex; jj--){}
+    if( jj>=0 ) continue;
+
+    /* Record that this index needs to be dropped.  Store the root page
+    ** number in SrcItem.regReturn so that indexes can be dropped largest
+    ** first to avoid problems with autovacuum reordering. */
+    pName->a[ii].u2.pIdx = pIndex;
     pName->a[ii].regReturn = pIndex->tnum;
 
-    /* Generate code to remove the index and from the schema table */
+    /* Generate code to remove the index and from the schema table and
+    ** from sqlite_statN tables */
     v = sqlite3GetVdbe(pParse);
     if( v==0 ) break;
     sqlite3BeginWriteOperation(pParse, 1, iDb);
@@ -4682,6 +4682,23 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
        db->aDb[iDb].zDbSName, pIndex->zName
     );
     sqlite3ClearStatTables(pParse, iDb, "idx", pIndex->zName);
+  }
+
+  /* Drop the indexes.  Drop the ones with the largest root page first
+  ** to avoid problems with autovacuum. */
+  while( pParse->nErr==0 ){
+    int iBest = 0;
+    jj = 0;
+    for(ii=0; ii<pName->nSrc; ii++){
+      if( pName->a[ii].regReturn>iBest ){
+        jj = ii;
+        iBest = pName->a[ii].regReturn;
+      }
+    }
+    if( iBest<=0 ) break;
+    pIndex = pName->a[jj].u2.pIdx;
+    pName->a[jj].regReturn = 0;
+    iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);
     sqlite3ChangeCookie(pParse, iDb);
     destroyRootPage(pParse, pIndex->tnum, iDb);
     sqlite3VdbeAddOp4(v, OP_DropIndex, iDb, 0, 0, pIndex->zName, 0);

diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 9a9a13f3766986579357140e3071efdfca5a6eef..f91f2d9ae3d1ffa1c3296209379b1d0d5a27ee4e 100644 (file)
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3315,6 +3315,7 @@ struct SrcItem {
     Index *pIBIndex;  /* Index structure corresponding to u1.zIndexedBy */
     CteUse *pCteUse;  /* CTE Usage info when fg.isCte is true */
     Trigger *pTrig;   /* Trigger in argument list of DROP TRIGGER */
+    Index *pIdx;      /* Index in argument list to DROP INDEX */
   } u2;
 };