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Size reduction and performance increase in defragementPage() of btree.c.

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FossilOrigin-Name: 1b03f197b5572084177012a58990f8dba7ff10382ff5657fda62867a4d0b1af9
This commit is contained in:
drh
2022-07-07 21:04:03 +00:00
parent ebaa9477d7
commit f15b77b7cf
3 changed files with 35 additions and 37 deletions
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58
src/btree.c
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@@ -1513,7 +1513,6 @@ static int defragmentPage(MemPage *pPage, int nMaxFrag){
assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
assert( pPage->nOverflow==0 );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
temp = 0;
src = data = pPage->aData;
hdr = pPage->hdrOffset;
cellOffset = pPage->cellOffset;
@@ -1568,39 +1567,38 @@ static int defragmentPage(MemPage *pPage, int nMaxFrag){
cbrk = usableSize;
iCellLast = usableSize - 4;
iCellStart = get2byte(&data[hdr+5]);
for(i=0; i<nCell; i++){
u8 *pAddr; /* The i-th cell pointer */
pAddr = &data[cellOffset + i*2];
pc = get2byte(pAddr);
testcase( pc==iCellFirst );
testcase( pc==iCellLast );
/* These conditions have already been verified in btreeInitPage()
** if PRAGMA cell_size_check=ON.
*/
if( pc<iCellStart || pc>iCellLast ){
return SQLITE_CORRUPT_PAGE(pPage);
if( nCell>0 ){
temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
memcpy(&temp[iCellStart], &data[iCellStart], usableSize - iCellStart);
src = temp;
for(i=0; i<nCell; i++){
u8 *pAddr; /* The i-th cell pointer */
pAddr = &data[cellOffset + i*2];
pc = get2byte(pAddr);
testcase( pc==iCellFirst );
testcase( pc==iCellLast );
/* These conditions have already been verified in btreeInitPage()
** if PRAGMA cell_size_check=ON.
*/
if( pc<iCellStart || pc>iCellLast ){
return SQLITE_CORRUPT_PAGE(pPage);
}
assert( pc>=iCellStart && pc<=iCellLast );
size = pPage->xCellSize(pPage, &src[pc]);
cbrk -= size;
if( cbrk<iCellStart || pc+size>usableSize ){
return SQLITE_CORRUPT_PAGE(pPage);
}
assert( cbrk+size<=usableSize && cbrk>=iCellStart );
testcase( cbrk+size==usableSize );
testcase( pc+size==usableSize );
put2byte(pAddr, cbrk);
memcpy(&data[cbrk], &src[pc], size);
}
assert( pc>=iCellStart && pc<=iCellLast );
size = pPage->xCellSize(pPage, &src[pc]);
cbrk -= size;
if( cbrk<iCellStart || pc+size>usableSize ){
return SQLITE_CORRUPT_PAGE(pPage);
}
assert( cbrk+size<=usableSize && cbrk>=iCellStart );
testcase( cbrk+size==usableSize );
testcase( pc+size==usableSize );
put2byte(pAddr, cbrk);
if( temp==0 ){
if( cbrk==pc ) continue;
temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
memcpy(&temp[iCellStart], &data[iCellStart], usableSize - iCellStart);
src = temp;
}
memcpy(&data[cbrk], &src[pc], size);
}
data[hdr+7] = 0;
defragment_out:
defragment_out:
assert( pPage->nFree>=0 );
if( data[hdr+7]+cbrk-iCellFirst!=pPage->nFree ){
return SQLITE_CORRUPT_PAGE(pPage);