Changes to the btree and pager that reduce the amount of I/O when dealing

with the freelist.  (1) Avoid journaling pages of a table that is being
deleted.  (2) Do not read the original content of pages being pulled off
of the freelist. (CVS 3671)

FossilOrigin-Name: 2ba5be311945a4c15b6dce7c01efefb513b9a973

diff --git a/manifest b/manifest
index 7a4b47c32967dce51eb3fc04f3d364800f1bd10d..4d199ddcd49d3bd791516ce22997bd3660ee5ab5 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Handle\sthe\scase\swhere\sthe\sestimated\scost\sof\sa\svirtual\stable\sscan\sis\slarger\sthan\sSQLITE_BIG_DBL.\sTicket\s#2253.\s(CVS\s3670)
-D 2007-03-02T08:12:22
+C Changes\sto\sthe\sbtree\sand\spager\sthat\sreduce\sthe\samount\sof\sI/O\swhen\sdealing\nwith\sthe\sfreelist.\s\s(1)\sAvoid\sjournaling\spages\sof\sa\stable\sthat\sis\sbeing\ndeleted.\s\s(2)\sDo\snot\sread\sthe\soriginal\scontent\sof\spages\sbeing\spulled\soff\nof\sthe\sfreelist.\s(CVS\s3671)
+D 2007-03-04T13:15:28
 F Makefile.in 1fe3d0b46e40fd684e1e61f8e8056cefed16de9f
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -57,7 +57,7 @@ F src/alter.c 2c79ec40f65e33deaf90ca493422c74586e481a3
 F src/analyze.c 7d2b7ab9a9c2fd6e55700f69064dfdd3e36d7a8a
 F src/attach.c b11eb4d5d3fb99a10a626956bccc7215f6b68b16
 F src/auth.c 902f4722661c796b97f007d9606bd7529c02597f
-F src/btree.c 4d4bef16fbf4f53ec3b161cfe5bb19bbc27a281d
+F src/btree.c 866536a3c667de942747ee3fd3914b31bb273fee
 F src/btree.h 066444ee25bd6e6accb997bfd2cf5ace14dbcd00
 F src/build.c 6bd68dc730b01c1727738f8e4b5c730eb0ddb421
 F src/callback.c 31d22b4919c7645cbcbb1591ce2453e8c677c558
@@ -85,8 +85,8 @@ F src/os_unix.c abdb0f7b8e3f078b8b48d4c0b8c801693046774d
 F src/os_unix.h 5768d56d28240d3fe4537fac08cc85e4fb52279e
 F src/os_win.c 8736cf3a49fd651a6538857480f302807d57814c
 F src/os_win.h 41a946bea10f61c158ce8645e7646b29d44f122b
-F src/pager.c 5d3a127c93489c93e59dfbb1be2b29e39e135f68
-F src/pager.h 2e6d42f4ae004ae748a037b8468112b851c447a7
+F src/pager.c c78d1cc1a02d9c6ab3263c3ca757e4466973fa2a
+F src/pager.h 8881591ca23d1e5fd83c95fa8317245fbcf64227
 F src/parse.y bcfe366c1fd61cfc40e5344eb69a31997a821af0
 F src/pragma.c 5091300911670ddaa552bfa12c45cbca1bb7e7d6
 F src/prepare.c 484389c6811415b8f23d259ac9c029613e1c72c3
@@ -435,7 +435,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P ddb4d0af5770c7030fe6e92119972c9508724b9a
-R 35703e5b3fc1d8c9b1249f60db5a29c1
-U danielk1977
-Z cc77ee9ae5f32f8281d9b31d7adeb8f2
+P 52885ed8b76a06588acf202a38b4feabfca1cfd1
+R 35bc70c2ff87b67600b039941003bc67
+U drh
+Z a8523f47620c390e8f111fe930472ba8

diff --git a/manifest.uuid b/manifest.uuid
index 6a83391b2fd83149dfbc237ea30486fbea8bf9ab..975c7d4dcb44f6656ebaca860f3f1403cfb75470 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-52885ed8b76a06588acf202a38b4feabfca1cfd1
\ No newline at end of file
+2ba5be311945a4c15b6dce7c01efefb513b9a973
\ No newline at end of file

diff --git a/src/btree.c b/src/btree.c
index 2a223df898912af731aa040c89ce29299ea51058..e3ec85a48572400103e26e5944429101e9ed8847 100644 (file)
--- a/src/btree.c
+++ b/src/btree.c
@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.335 2007/02/10 19:22:36 drh Exp $
+** $Id: btree.c,v 1.336 2007/03/04 13:15:28 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** For a detailed discussion of BTrees, refer to
@@ -1382,11 +1382,11 @@ static void zeroPage(MemPage *pPage, int flags){
 ** Get a page from the pager.  Initialize the MemPage.pBt and
 ** MemPage.aData elements if needed.
 */
-static int getPage(BtShared *pBt, Pgno pgno, MemPage **ppPage){
+static int getPage(BtShared *pBt, Pgno pgno, MemPage **ppPage, int clrFlag){
   int rc;
   unsigned char *aData;
   MemPage *pPage;
-  rc = sqlite3pager_get(pBt->pPager, pgno, (void**)&aData);
+  rc = sqlite3pager_acquire(pBt->pPager, pgno, (void**)&aData, clrFlag);
   if( rc ) return rc;
   pPage = (MemPage*)&aData[pBt->pageSize];
   pPage->aData = aData;
@@ -1412,7 +1412,7 @@ static int getAndInitPage(
   if( pgno==0 ){
     return SQLITE_CORRUPT_BKPT; 
   }
-  rc = getPage(pBt, pgno, ppPage);
+  rc = getPage(pBt, pgno, ppPage, 0);
   if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
     rc = initPage(*ppPage, pParent);
   }
@@ -1834,7 +1834,7 @@ static int lockBtree(BtShared *pBt){
   int rc, pageSize;
   MemPage *pPage1;
   if( pBt->pPage1 ) return SQLITE_OK;
-  rc = getPage(pBt, 1, &pPage1);
+  rc = getPage(pBt, 1, &pPage1, 0);
   if( rc!=SQLITE_OK ) return rc;
   
 
@@ -2237,7 +2237,7 @@ static int relocatePage(
   ** iPtrPage.
   */
   if( eType!=PTRMAP_ROOTPAGE ){
-    rc = getPage(pBt, iPtrPage, &pPtrPage);
+    rc = getPage(pBt, iPtrPage, &pPtrPage, 0);
     if( rc!=SQLITE_OK ){
       return rc;
     }
@@ -2341,7 +2341,7 @@ static int autoVacuumCommit(BtShared *pBt, Pgno *nTrunc){
     if( eType==PTRMAP_FREEPAGE ){
       continue;
     }
-    rc = getPage(pBt, iDbPage, &pDbMemPage);
+    rc = getPage(pBt, iDbPage, &pDbMemPage, 0);
     if( rc!=SQLITE_OK ) goto autovacuum_out;
 
     /* Find the next page in the free-list that is not already at the end 
@@ -2525,7 +2525,7 @@ int sqlite3BtreeRollback(Btree *p){
     /* The rollback may have destroyed the pPage1->aData value.  So
     ** call getPage() on page 1 again to make sure pPage1->aData is
     ** set correctly. */
-    if( getPage(pBt, 1, &pPage1)==SQLITE_OK ){
+    if( getPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
       releasePage(pPage1);
     }
     assert( countWriteCursors(pBt)==0 );
@@ -3618,7 +3618,7 @@ static int allocatePage(
       }else{
         iTrunk = get4byte(&pPage1->aData[32]);
       }
-      rc = getPage(pBt, iTrunk, &pTrunk);
+      rc = getPage(pBt, iTrunk, &pTrunk, 0);
       if( rc ){
         pTrunk = 0;
         goto end_allocate_page;
@@ -3668,7 +3668,7 @@ static int allocatePage(
           */
           MemPage *pNewTrunk;
           Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
-          rc = getPage(pBt, iNewTrunk, &pNewTrunk);
+          rc = getPage(pBt, iNewTrunk, &pNewTrunk, 0);
           if( rc!=SQLITE_OK ){
             goto end_allocate_page;
           }
@@ -3734,7 +3734,7 @@ static int allocatePage(
             memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
           }
           put4byte(&aData[4], k-1);
-          rc = getPage(pBt, *pPgno, ppPage);
+          rc = getPage(pBt, *pPgno, ppPage, 1);
           if( rc==SQLITE_OK ){
             sqlite3pager_dont_rollback((*ppPage)->aData);
             rc = sqlite3pager_write((*ppPage)->aData);
@@ -3766,7 +3766,7 @@ static int allocatePage(
 #endif
 
     assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
-    rc = getPage(pBt, *pPgno, ppPage);
+    rc = getPage(pBt, *pPgno, ppPage, 0);
     if( rc ) return rc;
     rc = sqlite3pager_write((*ppPage)->aData);
     if( rc!=SQLITE_OK ){
@@ -3835,7 +3835,7 @@ static int freePage(MemPage *pPage){
     /* Other free pages already exist.  Retrive the first trunk page
     ** of the freelist and find out how many leaves it has. */
     MemPage *pTrunk;
-    rc = getPage(pBt, get4byte(&pPage1->aData[32]), &pTrunk);
+    rc = getPage(pBt, get4byte(&pPage1->aData[32]), &pTrunk, 0);
     if( rc ) return rc;
     k = get4byte(&pTrunk->aData[4]);
     if( k>=pBt->usableSize/4 - 8 ){
@@ -3883,7 +3883,7 @@ static int clearCell(MemPage *pPage, unsigned char *pCell){
     if( ovflPgno>sqlite3pager_pagecount(pBt->pPager) ){
       return SQLITE_CORRUPT_BKPT;
     }
-    rc = getPage(pBt, ovflPgno, &pOvfl);
+    rc = getPage(pBt, ovflPgno, &pOvfl, 0);
     if( rc ) return rc;
     ovflPgno = get4byte(pOvfl->aData);
     rc = freePage(pOvfl);
@@ -3975,7 +3975,6 @@ static int fillInCell(
 #endif
       if( rc ){
         releasePage(pToRelease);
-        /* clearCell(pPage, pCell); */
         return rc;
       }
       put4byte(pPrior, pgnoOvfl);
@@ -4978,7 +4977,7 @@ static int balance_shallower(MemPage *pPage){
     pgnoChild = get4byte(&pPage->aData[pPage->hdrOffset+8]);
     assert( pgnoChild>0 );
     assert( pgnoChild<=sqlite3pager_pagecount(pPage->pBt->pPager) );
-    rc = getPage(pPage->pBt, pgnoChild, &pChild);
+    rc = getPage(pPage->pBt, pgnoChild, &pChild, 0);
     if( rc ) goto end_shallow_balance;
     if( pPage->pgno==1 ){
       rc = initPage(pChild, pPage);
@@ -5433,7 +5432,7 @@ int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
       Pgno iPtrPage;
 
       releasePage(pPageMove);
-      rc = getPage(pBt, pgnoRoot, &pRoot);
+      rc = getPage(pBt, pgnoRoot, &pRoot, 0);
       if( rc!=SQLITE_OK ){
         return rc;
       }
@@ -5454,7 +5453,7 @@ int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
       if( rc!=SQLITE_OK ){
         return rc;
       }
-      rc = getPage(pBt, pgnoRoot, &pRoot);
+      rc = getPage(pBt, pgnoRoot, &pRoot, 0);
       if( rc!=SQLITE_OK ){
         return rc;
       }
@@ -5512,8 +5511,6 @@ static int clearDatabasePage(
 
   rc = getAndInitPage(pBt, pgno, &pPage, pParent);
   if( rc ) goto cleardatabasepage_out;
-  rc = sqlite3pager_write(pPage->aData);
-  if( rc ) goto cleardatabasepage_out;
   for(i=0; i<pPage->nCell; i++){
     pCell = findCell(pPage, i);
     if( !pPage->leaf ){
@@ -5529,7 +5526,7 @@ static int clearDatabasePage(
   }
   if( freePageFlag ){
     rc = freePage(pPage);
-  }else{
+  }else if( (rc = sqlite3pager_write(pPage->aData))==0 ){
     zeroPage(pPage, pPage->aData[0] | PTF_LEAF);
   }
 
@@ -5605,7 +5602,7 @@ int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
     return SQLITE_LOCKED;
   }
 
-  rc = getPage(pBt, (Pgno)iTable, &pPage);
+  rc = getPage(pBt, (Pgno)iTable, &pPage, 0);
   if( rc ) return rc;
   rc = sqlite3BtreeClearTable(p, iTable);
   if( rc ){
@@ -5644,7 +5641,7 @@ int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
         */
         MemPage *pMove;
         releasePage(pPage);
-        rc = getPage(pBt, maxRootPgno, &pMove);
+        rc = getPage(pBt, maxRootPgno, &pMove, 0);
         if( rc!=SQLITE_OK ){
           return rc;
         }
@@ -5653,7 +5650,7 @@ int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
         if( rc!=SQLITE_OK ){
           return rc;
         }
-        rc = getPage(pBt, maxRootPgno, &pMove);
+        rc = getPage(pBt, maxRootPgno, &pMove, 0);
         if( rc!=SQLITE_OK ){
           return rc;
         }
@@ -5787,7 +5784,7 @@ static int btreePageDump(BtShared *pBt, int pgno, int recursive, MemPage *pParen
   char range[20];
   unsigned char payload[20];
 
-  rc = getPage(pBt, (Pgno)pgno, &pPage);
+  rc = getPage(pBt, (Pgno)pgno, &pPage, 0);
   isInit = pPage->isInit;
   if( pPage->isInit==0 ){
     initPage(pPage, pParent);
@@ -6168,7 +6165,7 @@ static int checkTreePage(
   usableSize = pBt->usableSize;
   if( iPage==0 ) return 0;
   if( checkRef(pCheck, iPage, zParentContext) ) return 0;
-  if( (rc = getPage(pBt, (Pgno)iPage, &pPage))!=0 ){
+  if( (rc = getPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
     checkAppendMsg(pCheck, zContext,
        "unable to get the page. error code=%d", rc);
     return 0;

diff --git a/src/pager.c b/src/pager.c
index d757f0106dc289c0731b94be0acfaae80f40b4f1..73f04af69ed2136be36fdc4485cc180e5052d3ce 100644 (file)
--- a/src/pager.c
+++ b/src/pager.c
@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.284 2007/03/01 00:29:14 drh Exp $
+** @(#) $Id: pager.c,v 1.285 2007/03/04 13:15:28 drh Exp $
 */
 #ifndef SQLITE_OMIT_DISKIO
 #include "sqliteInt.h"
@@ -2625,8 +2625,13 @@ int sqlite3pager_release_memory(int nReq){
 ** has to go to disk, and could also playback an old journal if necessary.
 ** Since _lookup() never goes to disk, it never has to deal with locks
 ** or journal files.
+**
+** If clrFlag is false, the page contents are actually read from disk.
+** If clfFlag is true, it means the page is about to be erased and
+** rewritten without first being read so there is no point it doing
+** the disk I/O.
 */
-int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
+int sqlite3pager_acquire(Pager *pPager, Pgno pgno, void **ppPage, int clrFlag){
   PgHdr *pPg;
   int rc;
 
@@ -2784,7 +2789,9 @@ int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
     /* Populate the page with data, either by reading from the database
     ** file, or by setting the entire page to zero.
     */
-    if( sqlite3pager_pagecount(pPager)<(int)pgno || MEMDB ){
+    if( sqlite3pager_pagecount(pPager)<(int)pgno || MEMDB
+         || (clrFlag && !pPager->alwaysRollback) 
+    ){
       memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
     }else{
       assert( MEMDB==0 );

diff --git a/src/pager.h b/src/pager.h
index ca5711457be404084db70c6cac6fcb5aa6a6e6bd..44825af408cc2af2f7596c86e3bea878854fbaa9 100644 (file)
--- a/src/pager.h
+++ b/src/pager.h
@@ -13,7 +13,7 @@
 ** subsystem.  The page cache subsystem reads and writes a file a page
 ** at a time and provides a journal for rollback.
 **
-** @(#) $Id: pager.h,v 1.52 2006/11/06 21:20:26 drh Exp $
+** @(#) $Id: pager.h,v 1.53 2007/03/04 13:15:28 drh Exp $
 */
 
 #ifndef _PAGER_H_
@@ -78,7 +78,8 @@ int sqlite3pager_set_pagesize(Pager*, int);
 int sqlite3pager_read_fileheader(Pager*, int, unsigned char*);
 void sqlite3pager_set_cachesize(Pager*, int);
 int sqlite3pager_close(Pager *pPager);
-int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage);
+int sqlite3pager_acquire(Pager *pPager, Pgno pgno, void **ppPage, int clrFlag);
+#define sqlite3pager_get(A,B,C) sqlite3pager_acquire(A,B,C,0)
 void *sqlite3pager_lookup(Pager *pPager, Pgno pgno);
 int sqlite3pager_ref(void*);
 int sqlite3pager_unref(void*);