The btree layer now tracks when a database is empty at the start of a

transaction and rolls back to that state.

FossilOrigin-Name: 01ef6c1944507c188a83a434ff00e98ad767f744

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Fix\sissues\swith\sthe\sio.test\sscript.\s\sThere\sis\sstill\sa\sproblem\swith\sa\nROLLBACK\sTO\snot\sworking\son\san\sinitially\sempty\sdatabase\sfiles.\s\sAnd\smuch\nmore\stesting\sis\sneeded.
-D 2010-03-29T19:36:52
+C The\sbtree\slayer\snow\stracks\swhen\sa\sdatabase\sis\sempty\sat\sthe\sstart\sof\sa\ntransaction\sand\srolls\sback\sto\sthat\sstate.
+D 2010-03-29T21:13:12
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 4f2f967b7e58a35bb74fb7ec8ae90e0f4ca7868b
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -112,9 +112,9 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c b293534bc2df23c57668a585b17ee7faaaef0939
 F src/bitvec.c 06ad2c36a9c3819c0b9cbffec7b15f58d5d834e0
 F src/btmutex.c 96a12f50f7a17475155971a241d85ec5171573ff
-F src/btree.c 6bb6cf7bed564d5a836888d49952d18991a8fe0d
+F src/btree.c ca75bce3383240f9fb14590ddfcd72883cc09609
 F src/btree.h 0e193b7e90f1d78b79c79474040e3d66a553a4fa
-F src/btreeInt.h 132d750db5d86b75344cec870501fa09a67b1f96
+F src/btreeInt.h 22447d259639271774a931cbf66aa55112846681
 F src/build.c 11100b66fb97638d2d874c1d34d8db90650bb1d7
 F src/callback.c 908f3e0172c3d4058f4ca0acd42c637c52e9669f
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
@@ -797,14 +797,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P b844ac6fcb72595a71e5c5283ec461309a87ba79
-R a62dd4e3ab32e20d939eda838bfbb2f1
+P 09786e2a51817d572a01ae7f3621f03fd27fc363
+R 374d4e1ebc45357833ef412064f83b3a
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manifest.uuid

@@ -1 +1 @@
-09786e2a51817d572a01ae7f3621f03fd27fc363
+01ef6c1944507c188a83a434ff00e98ad767f744

src/btree.c

@@ -2484,6 +2484,7 @@ int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
   rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
   if( SQLITE_OK!=rc ) goto trans_begun;
 
+  pBt->initiallyEmpty = pBt->nPage==0;
   do {
     /* Call lockBtree() until either pBt->pPage1 is populated or
     ** lockBtree() returns something other than SQLITE_OK. lockBtree()
@@ -3264,6 +3265,7 @@ int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
     sqlite3BtreeEnter(p);
     rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
     if( rc==SQLITE_OK ){
+      if( iSavepoint<0 && pBt->initiallyEmpty ) pBt->nPage = 0;
       rc = newDatabase(pBt);
       pBt->nPage = get4byte(28 + pBt->pPage1->aData);
     }

src/btreeInt.h

@@ -408,6 +408,7 @@ struct BtShared {
   u8 readOnly;          /* True if the underlying file is readonly */
   u8 pageSizeFixed;     /* True if the page size can no longer be changed */
   u8 secureDelete;      /* True if secure_delete is enabled */
+  u8 initiallyEmpty;    /* Database is empty at start of transaction */
 #ifndef SQLITE_OMIT_AUTOVACUUM
   u8 autoVacuum;        /* True if auto-vacuum is enabled */
   u8 incrVacuum;        /* True if incr-vacuum is enabled */