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Add the Mempage.aDataOfst field and use it in sqlite3BtreeMovetoUnpacked()

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for about a 2 million cycle gain.

FossilOrigin-Name: bee94dc3510745ba2efa044e8f3299793cfc7e34
This commit is contained in:
drh
2015-06-27 03:58:15 +00:00
parent 95ae9587f1
commit f44890a7c4
4 changed files with 20 additions and 11 deletions
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12
src/btree.c
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@@ -954,10 +954,16 @@ static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** findCellPastPtr() does the same except it skips past the initial
** 4-byte child pointer found on interior pages, if there is one.
**
** This routine works only for pages that do not contain overflow cells.
*/
#define findCell(P,I) \
((P)->aData + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))
#define findCellPastPtr(P,I) \
((P)->aDataOfst + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))
/*
** This is common tail processing for btreeParseCellPtr() and
@@ -1703,6 +1709,7 @@ static int btreeInitPage(MemPage *pPage){
pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize;
pPage->aDataEnd = &data[usableSize];
pPage->aCellIdx = &data[cellOffset];
pPage->aDataOfst = &data[pPage->childPtrSize];
/* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates
** the start of the cell content area. A zero value for this integer is
** interpreted as 65536. */
@@ -1822,6 +1829,7 @@ static void zeroPage(MemPage *pPage, int flags){
pPage->cellOffset = first;
pPage->aDataEnd = &data[pBt->usableSize];
pPage->aCellIdx = &data[first];
pPage->aDataOfst = &data[pPage->childPtrSize];
pPage->nOverflow = 0;
assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
pPage->maskPage = (u16)(pBt->pageSize - 1);
@@ -5014,7 +5022,7 @@ int sqlite3BtreeMovetoUnpacked(
if( xRecordCompare==0 ){
for(;;){
i64 nCellKey;
pCell = findCell(pPage, idx) + pPage->childPtrSize;
pCell = findCellPastPtr(pPage, idx);
if( pPage->intKeyLeaf ){
while( 0x80 <= *(pCell++) ){
if( pCell>=pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
@@ -5047,7 +5055,7 @@ int sqlite3BtreeMovetoUnpacked(
}else{
for(;;){
int nCell; /* Size of the pCell cell in bytes */
pCell = findCell(pPage, idx) + pPage->childPtrSize;
pCell = findCellPastPtr(pPage, idx);
/* The maximum supported page-size is 65536 bytes. This means that
** the maximum number of record bytes stored on an index B-Tree