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Overview
| Comment: | Performance improvements on memory copies inside of btree by moving 2 bytes at a time instead of just 1 byte at a time. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
897f56a158ebe62758c9998e4941ae04 |
| User & Date: | drh 2011-06-03 23:28:33 |
References
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2011-06-06
| ||
| 13:38 | Add assert() statements to verify that u16 pointers associated with the enhancement in [897f56a158] are always 2-byte aligned. (check-in: 98ccfa93 user: drh tags: trunk) | |
Context
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2011-06-04
| ||
| 01:43 | Performance improvement to the btree search routine. (check-in: 65db822f user: drh tags: trunk) | |
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2011-06-03
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| 23:28 | Performance improvements on memory copies inside of btree by moving 2 bytes at a time instead of just 1 byte at a time. (check-in: 897f56a1 user: drh tags: trunk) | |
| 21:34 | Performance enhancement to the blob-literal tokenizer. (check-in: 61aa2031 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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rc = freeSpace(pPage, pc, sz);
if( rc ){
*pRC = rc;
return;
}
endPtr = &data[pPage->cellOffset + 2*pPage->nCell - 2];
while( ptr<endPtr ){
ptr[0] = ptr[2];
ptr[1] = ptr[3];
ptr += 2;
}
pPage->nCell--;
put2byte(&data[hdr+3], pPage->nCell);
pPage->nFree += 2;
}
................................................................................
int idx = 0; /* Where to write new cell content in data[] */
int j; /* Loop counter */
int end; /* First byte past the last cell pointer in data[] */
int ins; /* Index in data[] where new cell pointer is inserted */
int cellOffset; /* Address of first cell pointer in data[] */
u8 *data; /* The content of the whole page */
u8 *ptr; /* Used for moving information around in data[] */
int nSkip = (iChild ? 4 : 0);
if( *pRC ) return;
assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 );
................................................................................
assert( idx+sz <= (int)pPage->pBt->usableSize );
pPage->nCell++;
pPage->nFree -= (u16)(2 + sz);
memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
if( iChild ){
put4byte(&data[idx], iChild);
}
for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){
ptr[0] = ptr[-2];
ptr[1] = ptr[-1];
}
put2byte(&data[ins], idx);
put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
#ifndef SQLITE_OMIT_AUTOVACUUM
if( pPage->pBt->autoVacuum ){
/* The cell may contain a pointer to an overflow page. If so, write
** the entry for the overflow page into the pointer map.
................................................................................
/* Check that the page has just been zeroed by zeroPage() */
assert( pPage->nCell==0 );
assert( get2byteNotZero(&data[hdr+5])==nUsable );
pCellptr = &data[pPage->cellOffset + nCell*2];
cellbody = nUsable;
for(i=nCell-1; i>=0; i--){
pCellptr -= 2;
cellbody -= aSize[i];
put2byte(pCellptr, cellbody);
memcpy(&data[cellbody], apCell[i], aSize[i]);
}
put2byte(&data[hdr+3], nCell);
put2byte(&data[hdr+5], cellbody);
pPage->nFree -= (nCell*2 + nUsable - cellbody);
pPage->nCell = (u16)nCell;
}
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5418 5419 5420 5421 5422 5423 5424 5425 5426 5427 5428 5429 5430 5431 5432 .... 5459 5460 5461 5462 5463 5464 5465 5466 5467 5468 5469 5470 5471 5472 5473 .... 5510 5511 5512 5513 5514 5515 5516 5517 5518 5519 5520 5521 5522 5523 5524 5525 5526 5527 5528 .... 5559 5560 5561 5562 5563 5564 5565 5566 5567 5568 5569 5570 5571 5572 5573 5574 5575 5576 5577 |
rc = freeSpace(pPage, pc, sz);
if( rc ){
*pRC = rc;
return;
}
endPtr = &data[pPage->cellOffset + 2*pPage->nCell - 2];
while( ptr<endPtr ){
*(u16*)ptr = *(u16*)&ptr[2];
ptr += 2;
}
pPage->nCell--;
put2byte(&data[hdr+3], pPage->nCell);
pPage->nFree += 2;
}
................................................................................
int idx = 0; /* Where to write new cell content in data[] */
int j; /* Loop counter */
int end; /* First byte past the last cell pointer in data[] */
int ins; /* Index in data[] where new cell pointer is inserted */
int cellOffset; /* Address of first cell pointer in data[] */
u8 *data; /* The content of the whole page */
u8 *ptr; /* Used for moving information around in data[] */
u8 *endPtr; /* End of the loop */
int nSkip = (iChild ? 4 : 0);
if( *pRC ) return;
assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 );
................................................................................
assert( idx+sz <= (int)pPage->pBt->usableSize );
pPage->nCell++;
pPage->nFree -= (u16)(2 + sz);
memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
if( iChild ){
put4byte(&data[idx], iChild);
}
ptr = &data[end];
endPtr = &data[ins];
while( ptr>endPtr ){
*(u16*)ptr = *(u16*)&ptr[-2];
ptr -= 2;
}
put2byte(&data[ins], idx);
put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
#ifndef SQLITE_OMIT_AUTOVACUUM
if( pPage->pBt->autoVacuum ){
/* The cell may contain a pointer to an overflow page. If so, write
** the entry for the overflow page into the pointer map.
................................................................................
/* Check that the page has just been zeroed by zeroPage() */
assert( pPage->nCell==0 );
assert( get2byteNotZero(&data[hdr+5])==nUsable );
pCellptr = &data[pPage->cellOffset + nCell*2];
cellbody = nUsable;
for(i=nCell-1; i>=0; i--){
u16 sz = aSize[i];
pCellptr -= 2;
cellbody -= sz;
put2byte(pCellptr, cellbody);
memcpy(&data[cellbody], apCell[i], sz);
}
put2byte(&data[hdr+3], nCell);
put2byte(&data[hdr+5], cellbody);
pPage->nFree -= (nCell*2 + nUsable - cellbody);
pPage->nCell = (u16)nCell;
}
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