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Sync all version 3 changes. (CVS 1309)

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FossilOrigin-Name: 51892d6cdc739bb049fdfce8301354312167c181
This commit is contained in:
drh
2004-04-29 14:42:46 +00:00
parent 3aac2dd7bc
commit 8856d6aad2
3 changed files with 63 additions and 24 deletions
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73
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 1.105 2004/04/26 14:10:21 drh Exp $
** $Id: btree.c,v 1.106 2004/04/29 14:42:46 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
@@ -1519,6 +1519,22 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
return SQLITE_OK;
}
/*
** Return true if the page is the virtual root of its table.
**
** The virtual root page is the root page for most tables. But
** for the table rooted on page 1, sometime the real root page
** is empty except for the right-pointer. In such cases the
** virtual root page is the page that the right-pointer of page
** 1 is pointing to.
*/
static int isRootPage(MemPage *pPage){
MemPage *pParent = pPage->pParent;
assert( pParent==0 || pParent->isInit );
if( pParent || (pParent->pgno==1 && pParent->nCell==0) ) return 1;
return 0;
}
/*
** Move the cursor up to the parent page.
**
@@ -1535,6 +1551,7 @@ static void moveToParent(BtCursor *pCur){
pPage = pCur->pPage;
assert( pPage!=0 );
assert( !isRootPage(pPage) );
pParent = pPage->pParent;
assert( pParent!=0 );
idxParent = pPage->idxParent;
@@ -1580,14 +1597,21 @@ static int moveToRoot(BtCursor *pCur){
int rc;
Btree *pBt = pCur->pBt;
rc = sqlitepager_get(pBt->pPager, pCur->pgnoRoot, &pRoot);
rc = getPage(pBt, pCur->pgnoRoot, &pRoot);
if( rc ) return rc;
rc = initPage(pRoot, 0);
if( rc ) return rc;
releasePage(pCur->pPage);
pCur->pPage = pRoot;
pCur->idx = 0;
return SQLITE_OK;
if( pRoot->nCell==0 && !pRoot->leaf ){
Pgno subpage;
assert( pRoot->pgno==1 );
subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+6]);
assert( subpage>0 );
rc = movetoChild(pCur, subpage);
}
return rc;
}
/*
@@ -1802,7 +1826,7 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
return rc;
}
do{
if( pPage->pParent==0 ){
if( isRootPage(pPage) ){
*pRes = 1;
return SQLITE_OK;
}
@@ -1855,7 +1879,7 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
rc = moveToRightmost(pCur);
}else{
while( pCur->idx==0 ){
if( pPage->pParent==0 ){
if( isRootPage(pPage) ){
if( pRes ) *pRes = 1;
return SQLITE_OK;
}
@@ -2374,20 +2398,35 @@ static int balance(Btree *pBt, MemPage *pPage, BtCursor *pCur){
MemPage *pChild;
assert( pPage->isInit );
if( pPage->nCell==0 ){
if( pPage->u.hdr.rightChild ){
/*
** The root page is empty. Copy the one child page
** into the root page and return. This reduces the depth
** of the BTree by one.
if( pPage->leaf ){
/* The table is completely empty */
relinkCellList(pPage);
}else{
/* The root page is empty but has one child. Transfer the
** information from that one child into the root page if it
** will fit. This reduces the depth of the BTree by one.
**
** If the root page is page 1, it has less space available than
** the child, so it might not be able to hold all of the information
** in the child. If this is the case, then do not do the transfer.
** Leave page 1 empty except for the right-pointer to the child page.
** The child page becomes the virtual root of the tree.
*/
pgnoChild = SWAB32(pBt, pPage->u.hdr.rightChild);
rc = sqlitepager_get(pBt->pPager, pgnoChild, (void**)&pChild);
pgnoChild = get4byte(pPage->aData[pPage->hdrOffset+6]);
assert( pgnoChild>0 && pgnoChild<=sqlit3pager_pagecount(pBt->pPager) );
rc = getPage(pBt, pgnoChild, &pChild);
if( rc ) return rc;
memcpy(pPage, pChild, SQLITE_USABLE_SIZE);
pPage->isInit = 0;
rc = initPage(pBt, pPage, sqlitepager_pagenumber(pPage), 0);
assert( rc==SQLITE_OK );
reparentChildPages(pBt, pPage);
if( pPage->pgno==1 ){
rc = initPage(pChild);
if( rc ) return rc;
if( pChild->nFree>=100 ){
}
}else{
memcpy(pPage, pChild, SQLITE_USABLE_SIZE);
pPage->isInit = 0;
rc = initPage(pBt, pPage, sqlitepager_pagenumber(pPage), 0);
assert( rc==SQLITE_OK );
reparentChildPages(pBt, pPage);
if( pCur && pCur->pPage==pChild ){
sqlitepager_unref(pChild);
pCur->pPage = pPage;