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Performance optimization to the moveToRoot() subroutine in btree.c.

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FossilOrigin-Name: b5842a70f8e26456a8f0d39539bc266f097480a4
This commit is contained in:
drh
2013-12-06 23:25:27 +00:00
parent b8a9bb4fb9
commit 4e8fe3ff91
3 changed files with 13 additions and 17 deletions
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16
src/btree.c
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@@ -4395,8 +4395,6 @@ static void moveToParent(BtCursor *pCur){
static int moveToRoot(BtCursor *pCur){
MemPage *pRoot;
int rc = SQLITE_OK;
Btree *p = pCur->pBtree;
BtShared *pBt = p->pBt;
assert( cursorHoldsMutex(pCur) );
assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
@@ -4411,16 +4409,12 @@ static int moveToRoot(BtCursor *pCur){
}
if( pCur->iPage>=0 ){
int i;
for(i=1; i<=pCur->iPage; i++){
releasePage(pCur->apPage[i]);
}
pCur->iPage = 0;
while( pCur->iPage ) releasePage(pCur->apPage[pCur->iPage--]);
}else if( pCur->pgnoRoot==0 ){
pCur->eState = CURSOR_INVALID;
return SQLITE_OK;
}else{
rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0],
rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->apPage[0],
pCur->wrFlag==0 ? PAGER_GET_READONLY : 0);
if( rc!=SQLITE_OK ){
pCur->eState = CURSOR_INVALID;
@@ -4453,14 +4447,16 @@ static int moveToRoot(BtCursor *pCur){
pCur->atLast = 0;
pCur->validNKey = 0;
if( pRoot->nCell==0 && !pRoot->leaf ){
if( pRoot->nCell>0 ){
pCur->eState = CURSOR_VALID;
}else if( !pRoot->leaf ){
Pgno subpage;
if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
pCur->eState = CURSOR_VALID;
rc = moveToChild(pCur, subpage);
}else{
pCur->eState = ((pRoot->nCell>0)?CURSOR_VALID:CURSOR_INVALID);
pCur->eState = CURSOR_INVALID;
}
return rc;
}