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Overview
| Comment: | Make SQLITE_DIRECT_OVERFLOW_READ work for in WAL mode as long as the page being read is not in the the -wal file. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
9879be1899adf5634f551a2077b15ccb |
| User & Date: | drh 2017-01-26 02:26:02 |
Context
|
2017-01-26
| ||
| 16:27 | Minor simplification and performance optimization for Direct Overflow Read. check-in: 3e96d6ef user: drh tags: trunk | |
| 02:26 | Make SQLITE_DIRECT_OVERFLOW_READ work for in WAL mode as long as the page being read is not in the the -wal file. check-in: 9879be18 user: drh tags: trunk | |
| 01:54 | Enhancements to the kvtest utility program. Add the --jmode option. Improved output formatting. check-in: 62a4851c user: drh tags: trunk | |
Changes
Changes to src/btree.c.
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#ifdef SQLITE_DIRECT_OVERFLOW_READ
/* If all the following are true:
**
** 1) this is a read operation, and
** 2) data is required from the start of this overflow page, and
** 3) the database is file-backed, and
** 4) there is no open write-transaction, and
** 5) the database is not a WAL database,
** 6) all data from the page is being read.
** 7) at least 4 bytes have already been read into the output buffer
**
** then data can be read directly from the database file into the
** output buffer, bypassing the page-cache altogether. This speeds
** up loading large records that span many overflow pages.
*/
if( (eOp&0x01)==0 /* (1) */
&& offset==0 /* (2) */
&& (bEnd || a==ovflSize) /* (6) */
&& pBt->inTransaction==TRANS_READ /* (4) */
&& (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (3) */
&& 0==sqlite3PagerUseWal(pBt->pPager) /* (5) */
&& &pBuf[-4]>=pBufStart /* (7) */
){
u8 aSave[4];
u8 *aWrite = &pBuf[-4];
assert( aWrite>=pBufStart ); /* hence (7) */
memcpy(aSave, aWrite, 4);
rc = sqlite3OsRead(fd, aWrite, a+4, (i64)pBt->pageSize*(nextPage-1));
|
| | |
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#ifdef SQLITE_DIRECT_OVERFLOW_READ
/* If all the following are true:
**
** 1) this is a read operation, and
** 2) data is required from the start of this overflow page, and
** 3) the database is file-backed, and
** 4) there is no open write-transaction, and
** 5) the page is not in the WAL file
** 6) all data from the page is being read.
** 7) at least 4 bytes have already been read into the output buffer
**
** then data can be read directly from the database file into the
** output buffer, bypassing the page-cache altogether. This speeds
** up loading large records that span many overflow pages.
*/
if( (eOp&0x01)==0 /* (1) */
&& offset==0 /* (2) */
&& (bEnd || a==ovflSize) /* (6) */
&& pBt->inTransaction==TRANS_READ /* (4) */
&& (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (3) */
&& 0==sqlite3PagerUseWal(pBt->pPager, nextPage) /* (5) */
&& &pBuf[-4]>=pBufStart /* (7) */
){
u8 aSave[4];
u8 *aWrite = &pBuf[-4];
assert( aWrite>=pBufStart ); /* hence (7) */
memcpy(aSave, aWrite, 4);
rc = sqlite3OsRead(fd, aWrite, a+4, (i64)pBt->pageSize*(nextPage-1));
|
Changes to src/pager.c.
810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 |
** instead of
**
** if( pPager->jfd->pMethods ){ ...
*/
#define isOpen(pFd) ((pFd)->pMethods!=0)
/*
** Return true if this pager uses a write-ahead log instead of the usual
** rollback journal. Otherwise false.
*/
#ifndef SQLITE_OMIT_WAL
int sqlite3PagerUseWal(Pager *pPager){
return (pPager->pWal!=0);
}
# define pagerUseWal(x) sqlite3PagerUseWal(x)
#else
# define pagerUseWal(x) 0
# define pagerRollbackWal(x) 0
# define pagerWalFrames(v,w,x,y) 0
# define pagerOpenWalIfPresent(z) SQLITE_OK
# define pagerBeginReadTransaction(z) SQLITE_OK
#endif
|
| | | | > > | > > > > | |
810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 |
** instead of
**
** if( pPager->jfd->pMethods ){ ...
*/
#define isOpen(pFd) ((pFd)->pMethods!=0)
/*
** Return true if this pager uses a write-ahead log to read page pgno.
** Return false if the pager reads pgno directly from the database.
*/
#if !defined(SQLITE_OMIT_WAL) && defined(SQLITE_DIRECT_OVERFLOW_READ)
int sqlite3PagerUseWal(Pager *pPager, Pgno pgno){
u32 iRead = 0;
int rc;
if( pPager->pWal==0 ) return 0;
rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iRead);
return rc || iRead;
}
#endif
#ifndef SQLITE_OMIT_WAL
# define pagerUseWal(x) ((x)->pWal!=0)
#else
# define pagerUseWal(x) 0
# define pagerRollbackWal(x) 0
# define pagerWalFrames(v,w,x,y) 0
# define pagerOpenWalIfPresent(z) SQLITE_OK
# define pagerBeginReadTransaction(z) SQLITE_OK
#endif
|
Changes to src/pager.h.
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#ifndef SQLITE_OMIT_WAL int sqlite3PagerCheckpoint(Pager *pPager, sqlite3*, int, int*, int*); int sqlite3PagerWalSupported(Pager *pPager); int sqlite3PagerWalCallback(Pager *pPager); int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen); int sqlite3PagerCloseWal(Pager *pPager, sqlite3*); int sqlite3PagerUseWal(Pager *pPager); # ifdef SQLITE_ENABLE_SNAPSHOT int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot); int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot); int sqlite3PagerSnapshotRecover(Pager *pPager); # endif #else # define sqlite3PagerUseWal(x) 0 #endif #ifdef SQLITE_ENABLE_ZIPVFS int sqlite3PagerWalFramesize(Pager *pPager); #endif /* Functions used to query pager state and configuration. */ |
> | > | |
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#ifndef SQLITE_OMIT_WAL int sqlite3PagerCheckpoint(Pager *pPager, sqlite3*, int, int*, int*); int sqlite3PagerWalSupported(Pager *pPager); int sqlite3PagerWalCallback(Pager *pPager); int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen); int sqlite3PagerCloseWal(Pager *pPager, sqlite3*); # ifdef SQLITE_DIRECT_OVERFLOW_READ int sqlite3PagerUseWal(Pager *pPager, Pgno); # endif # ifdef SQLITE_ENABLE_SNAPSHOT int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot); int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot); int sqlite3PagerSnapshotRecover(Pager *pPager); # endif #else # define sqlite3PagerUseWal(x,y) 0 #endif #ifdef SQLITE_ENABLE_ZIPVFS int sqlite3PagerWalFramesize(Pager *pPager); #endif /* Functions used to query pager state and configuration. */ |