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Overview
| Comment: | Performance optimization to pageFindSlot() in the b-tree layer. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
59560d079fab4b91ec50855cc60349da |
| User & Date: | drh 2017-08-23 23:09:03 |
References
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2017-08-25
| ||
| 13:02 | Convert a branch made unreachable by [59560d07] into an assert(). check-in: 2738b8db user: drh tags: trunk | |
Context
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2017-08-24
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| 13:55 | Make sure the sqlite3_result_pointer() interface does not leave a VM register in an inconsistent state. Fix for ticket [7486aa54b968e9b5]. Test cases are in TH3. check-in: d2f9230c user: drh tags: trunk | |
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2017-08-23
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| 23:09 | Performance optimization to pageFindSlot() in the b-tree layer. check-in: 59560d07 user: drh tags: trunk | |
| 20:36 | Size and performance optimization to dropCell() and freeSpace(). check-in: bc1ec123 user: drh tags: trunk | |
Changes
Changes to src/btree.c.
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static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
const int hdr = pPg->hdrOffset;
u8 * const aData = pPg->aData;
int iAddr = hdr + 1;
int pc = get2byte(&aData[iAddr]);
int x;
int usableSize = pPg->pBt->usableSize;
assert( pc>0 );
do{
int size; /* Size of the free slot */
/* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
** increasing offset. */
if( pc>usableSize-4 || pc<iAddr+4 ){
*pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
return 0;
}
/* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
** freeblock form a big-endian integer which is the size of the freeblock
** in bytes, including the 4-byte header. */
size = get2byte(&aData[pc+2]);
if( (x = size - nByte)>=0 ){
testcase( x==4 );
testcase( x==3 );
................................................................................
** for the portion used by the new allocation. */
put2byte(&aData[pc+2], x);
}
return &aData[pc + x];
}
iAddr = pc;
pc = get2byte(&aData[pc]);
}while( pc );
return 0;
}
/*
** Allocate nByte bytes of space from within the B-Tree page passed
** as the first argument. Write into *pIdx the index into pPage->aData[]
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static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
const int hdr = pPg->hdrOffset;
u8 * const aData = pPg->aData;
int iAddr = hdr + 1;
int pc = get2byte(&aData[iAddr]);
int x;
int usableSize = pPg->pBt->usableSize;
int size; /* Size of the free slot */
assert( pc>0 );
while( pc<=usableSize-4 ){
/* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
** freeblock form a big-endian integer which is the size of the freeblock
** in bytes, including the 4-byte header. */
size = get2byte(&aData[pc+2]);
if( (x = size - nByte)>=0 ){
testcase( x==4 );
testcase( x==3 );
................................................................................
** for the portion used by the new allocation. */
put2byte(&aData[pc+2], x);
}
return &aData[pc + x];
}
iAddr = pc;
pc = get2byte(&aData[pc]);
if( pc<iAddr+size ) break;
}
if( pc ){
*pRc = SQLITE_CORRUPT_PGNO(pPg->pgno);
}
return 0;
}
/*
** Allocate nByte bytes of space from within the B-Tree page passed
** as the first argument. Write into *pIdx the index into pPage->aData[]
|