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Bias the b-tree binary search toward the high end. The common case is to

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append data and this heuristic makes append run much faster because there
are fewer comparisons. (CVS 3740)

FossilOrigin-Name: a9877f616b24737152627841fcbd80cc28426f1e
This commit is contained in:
drh
2007-03-29 04:43:26 +00:00
parent b7bac72350
commit f1d68b3096
3 changed files with 14 additions and 16 deletions
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16
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.343 2007/03/27 14:05:23 drh Exp $
** $Id: btree.c,v 1.344 2007/03/29 04:43:26 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
@@ -3305,12 +3305,10 @@ int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
*/
int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
int rc;
int tryRightmost;
rc = moveToRoot(pCur);
if( rc ) return rc;
assert( pCur->pPage );
assert( pCur->pPage->isInit );
tryRightmost = pCur->pPage->intKey;
if( pCur->eState==CURSOR_INVALID ){
*pRes = -1;
assert( pCur->pPage->nCell==0 );
@@ -3326,16 +3324,13 @@ int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
if( !pPage->intKey && pKey==0 ){
return SQLITE_CORRUPT_BKPT;
}
while( lwr<=upr ){
pCur->idx = upr;
if( lwr<=upr ) for(;;){
void *pCellKey;
i64 nCellKey;
pCur->idx = (lwr+upr)/2;
pCur->info.nSize = 0;
if( pPage->intKey ){
u8 *pCell;
if( tryRightmost ){
pCur->idx = upr;
}
pCell = findCell(pPage, pCur->idx) + pPage->childPtrSize;
if( pPage->hasData ){
u32 dummy;
@@ -3346,7 +3341,6 @@ int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
c = -1;
}else if( nCellKey>nKey ){
c = +1;
tryRightmost = 0;
}else{
c = 0;
}
@@ -3380,6 +3374,10 @@ int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
}else{
upr = pCur->idx-1;
}
if( lwr>upr ){
break;
}
pCur->idx = (lwr+upr)/2;
}
assert( lwr==upr+1 );
assert( pPage->isInit );