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

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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
This commit is contained in:
drh
2007-03-04 13:15:27 +00:00
parent 8efe541f24
commit 0787db6519
5 changed files with 46 additions and 41 deletions
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49
src/btree.c
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@@ -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;