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Overview
| Comment: | Remove an unnecessary conditional, replacing it with an assert(). Improvements to comments. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | overflow-pgno-cache |
| Files: | files | file ages | folders |
| SHA1: |
834bf1c367e1ccd498c7f9f843be2d2a |
| User & Date: | drh 2014-04-01 01:24:34.512 |
Context
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2014-04-04
| ||
| 18:49 | Performance improvements when reading large blobs, especially if SQLITE_DIRECT_OVERFLOW_READ is defined. (check-in: 2312eb6a9e user: drh tags: trunk) | |
|
2014-04-01
| ||
| 01:24 | Remove an unnecessary conditional, replacing it with an assert(). Improvements to comments. (Closed-Leaf check-in: 834bf1c367 user: drh tags: overflow-pgno-cache) | |
|
2014-03-31
| ||
| 23:57 | Fix a compiler warning when SQLITE_DIRECT_OVERFLOW_READ is defined. Minor performance enhancement and size reduction. (check-in: 96385dc460 user: drh tags: overflow-pgno-cache) | |
Changes
Changes to src/btree.c.
| ︙ | ︙ | |||
3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 | int bEnd; /* True if reading to end of data */ #endif assert( pPage ); assert( pCur->eState==CURSOR_VALID ); assert( pCur->aiIdx[pCur->iPage]<pPage->nCell ); assert( cursorHoldsMutex(pCur) ); getCellInfo(pCur); aPayload = pCur->info.pCell + pCur->info.nHeader; nKey = (pPage->intKey ? 0 : (int)pCur->info.nKey); #ifdef SQLITE_DIRECT_OVERFLOW_READ bEnd = (offset+amt==nKey+pCur->info.nData); #endif | > | 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 3984 | int bEnd; /* True if reading to end of data */ #endif assert( pPage ); assert( pCur->eState==CURSOR_VALID ); assert( pCur->aiIdx[pCur->iPage]<pPage->nCell ); assert( cursorHoldsMutex(pCur) ); assert( eOp!=2 || offset==0 ); /* Always start from beginning for eOp==2 */ getCellInfo(pCur); aPayload = pCur->info.pCell + pCur->info.nHeader; nKey = (pPage->intKey ? 0 : (int)pCur->info.nKey); #ifdef SQLITE_DIRECT_OVERFLOW_READ bEnd = (offset+amt==nKey+pCur->info.nData); #endif |
| ︙ | ︙ | |||
4005 4006 4007 4008 4009 4010 4011 |
if( rc==SQLITE_OK && amt>0 ){
const u32 ovflSize = pBt->usableSize - 4; /* Bytes content per ovfl page */
Pgno nextPage;
nextPage = get4byte(&aPayload[pCur->info.nLocal]);
| < | > > | | | | | 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023 4024 4025 4026 |
if( rc==SQLITE_OK && amt>0 ){
const u32 ovflSize = pBt->usableSize - 4; /* Bytes content per ovfl page */
Pgno nextPage;
nextPage = get4byte(&aPayload[pCur->info.nLocal]);
/* If the BtCursor.aOverflow[] has not been allocated, allocate it now.
** Except, do not allocate aOverflow[] for eOp==2.
**
** The aOverflow[] array is sized at one entry for each overflow page
** in the overflow chain. The page number of the first overflow page is
** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array
** means "not yet known" (the cache is lazily populated).
*/
if( eOp!=2 && (pCur->curFlags & BTCF_ValidOvfl)==0 ){
int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize;
if( nOvfl>pCur->nOvflAlloc ){
Pgno *aNew = (Pgno*)sqlite3DbRealloc(
pCur->pBtree->db, pCur->aOverflow, nOvfl*2*sizeof(Pgno)
);
|
| ︙ | ︙ | |||
4055 4056 4057 4058 4059 4060 4061 4062 |
if( offset>=ovflSize ){
/* The only reason to read this page is to obtain the page
** number for the next page in the overflow chain. The page
** data is not required. So first try to lookup the overflow
** page-list cache, if any, then fall back to the getOverflowPage()
** function.
*/
| > > > > | > | > | 4057 4058 4059 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 4081 |
if( offset>=ovflSize ){
/* The only reason to read this page is to obtain the page
** number for the next page in the overflow chain. The page
** data is not required. So first try to lookup the overflow
** page-list cache, if any, then fall back to the getOverflowPage()
** function.
**
** Note that the aOverflow[] array must be allocated because eOp!=2
** here. If eOp==2, then offset==0 and this branch is never taken.
*/
assert( eOp!=2 );
assert( pCur->curFlags & BTCF_ValidOvfl );
if( pCur->aOverflow[iIdx+1] ){
nextPage = pCur->aOverflow[iIdx+1];
}else{
rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
}
offset -= ovflSize;
}else{
/* Need to read this page properly. It contains some of the
** range of data that is being read (eOp==0) or written (eOp!=0).
*/
#ifdef SQLITE_DIRECT_OVERFLOW_READ
sqlite3_file *fd;
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