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Overview
| Comment: | Do not read the last page of a overflow chain when deleting that chain. Just add the page to the freelist. This reduces I/O. (CVS 3672) |
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| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
6db945f7a7587c8c7adada92f94ac793 |
| User & Date: | drh 2007-03-06 11:42:19.000 |
Context
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2007-03-06
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| 13:46 | Use heap instead of stack for large buffers in the pager. Fix for #2262. (CVS 3673) (check-in: dfe1dffa45 user: danielk1977 tags: trunk) | |
| 11:42 | Do not read the last page of a overflow chain when deleting that chain. Just add the page to the freelist. This reduces I/O. (CVS 3672) (check-in: 6db945f7a7 user: drh tags: trunk) | |
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2007-03-04
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| 13:15 | 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) (check-in: 2ba5be3119 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
1 2 3 4 5 6 7 8 9 10 11 | /* ** 2004 April 6 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | /* ** 2004 April 6 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** $Id: btree.c,v 1.337 2007/03/06 11:42:19 drh Exp $ ** ** This file implements a external (disk-based) database using BTrees. ** For a detailed discussion of BTrees, refer to ** ** Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3: ** "Sorting And Searching", pages 473-480. Addison-Wesley ** Publishing Company, Reading, Massachusetts. |
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1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 | if( rc ) return rc; pPage = (MemPage*)&aData[pBt->pageSize]; pPage->aData = aData; pPage->pBt = pBt; pPage->pgno = pgno; pPage->hdrOffset = pPage->pgno==1 ? 100 : 0; *ppPage = pPage; return SQLITE_OK; } /* ** Get a page from the pager and initialize it. This routine ** is just a convenience wrapper around separate calls to ** getPage() and initPage(). | > > > | 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 |
if( rc ) return rc;
pPage = (MemPage*)&aData[pBt->pageSize];
pPage->aData = aData;
pPage->pBt = pBt;
pPage->pgno = pgno;
pPage->hdrOffset = pPage->pgno==1 ? 100 : 0;
*ppPage = pPage;
if( clrFlag ){
sqlite3pager_dont_rollback(aData);
}
return SQLITE_OK;
}
/*
** Get a page from the pager and initialize it. This routine
** is just a convenience wrapper around separate calls to
** getPage() and initPage().
|
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3732 3733 3734 3735 3736 3737 3738 |
*pPgno, closest+1, k, pTrunk->pgno, n-1));
if( closest<k-1 ){
memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
}
put4byte(&aData[4], k-1);
rc = getPage(pBt, *pPgno, ppPage, 1);
if( rc==SQLITE_OK ){
| < | 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 |
*pPgno, closest+1, k, pTrunk->pgno, n-1));
if( closest<k-1 ){
memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
}
put4byte(&aData[4], k-1);
rc = getPage(pBt, *pPgno, ppPage, 1);
if( rc==SQLITE_OK ){
rc = sqlite3pager_write((*ppPage)->aData);
if( rc!=SQLITE_OK ){
releasePage(*ppPage);
}
}
searchList = 0;
}
|
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3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 |
** Free any overflow pages associated with the given Cell.
*/
static int clearCell(MemPage *pPage, unsigned char *pCell){
BtShared *pBt = pPage->pBt;
CellInfo info;
Pgno ovflPgno;
int rc;
parseCellPtr(pPage, pCell, &info);
if( info.iOverflow==0 ){
return SQLITE_OK; /* No overflow pages. Return without doing anything */
}
ovflPgno = get4byte(&pCell[info.iOverflow]);
while( ovflPgno!=0 ){
MemPage *pOvfl;
if( ovflPgno>sqlite3pager_pagecount(pBt->pPager) ){
return SQLITE_CORRUPT_BKPT;
}
| > > > > > > > | > | 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901 3902 3903 3904 3905 3906 3907 3908 3909 |
** Free any overflow pages associated with the given Cell.
*/
static int clearCell(MemPage *pPage, unsigned char *pCell){
BtShared *pBt = pPage->pBt;
CellInfo info;
Pgno ovflPgno;
int rc;
int nOvfl;
int ovflPageSize;
int nPayload;
parseCellPtr(pPage, pCell, &info);
if( info.iOverflow==0 ){
return SQLITE_OK; /* No overflow pages. Return without doing anything */
}
ovflPgno = get4byte(&pCell[info.iOverflow]);
nPayload = pPage->intKey ? info.nData : info.nKey;
ovflPageSize = pBt->usableSize - 4;
nOvfl = (nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
while( ovflPgno!=0 ){
MemPage *pOvfl;
nOvfl--;
if( ovflPgno>sqlite3pager_pagecount(pBt->pPager) ){
return SQLITE_CORRUPT_BKPT;
}
rc = getPage(pBt, ovflPgno, &pOvfl, nOvfl==0);
if( rc ) return rc;
ovflPgno = get4byte(pOvfl->aData);
rc = freePage(pOvfl);
sqlite3pager_unref(pOvfl->aData);
if( rc ) return rc;
}
assert( nOvfl==0 );
return SQLITE_OK;
}
/*
** Create the byte sequence used to represent a cell on page pPage
** and write that byte sequence into pCell[]. Overflow pages are
** allocated and filled in as necessary. The calling procedure
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