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Add support for table allocation (not deallocation) in auto-vacuum databases. (CVS 2051)

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FossilOrigin-Name: 571de52376f52999268ba5e0cd05c6c6eff1ebbf
This commit is contained in:
danielk1977
2004-11-04 02:57:33 +00:00
parent 6bf895708c
commit 003ba061da
4 changed files with 201 additions and 60 deletions
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208
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 1.202 2004/11/03 11:37:08 danielk1977 Exp $
** $Id: btree.c,v 1.203 2004/11/04 02:57:34 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
@@ -1426,6 +1426,11 @@ static int newDatabase(Btree *pBt){
memset(&data[24], 0, 100-24);
zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
if( pBt->autoVacuum ){
put4byte(&data[36 + 4*4], 1);
}
#endif
return SQLITE_OK;
}
@@ -1606,6 +1611,74 @@ static void modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
}
}
static int relocatePage(
Btree *pBt,
MemPage *pDbPage,
u8 eType,
Pgno iPtrPage,
Pgno iFreePage
){
MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */
Pgno iDbPage = pDbPage->pgno;
Pager *pPager = pBt->pPager;
int rc;
assert( eType==PTRMAP_OVERFLOW2
|| eType==PTRMAP_OVERFLOW1 || eType==PTRMAP_BTREE );
/* Move page iDbPage from it's current location to page number iFreePage */
TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
iDbPage, iFreePage, iPtrPage, eType));
rc = sqlite3pager_movepage(pPager, pDbPage->aData, iFreePage);
if( rc!=SQLITE_OK ){
return rc;
}
pDbPage->pgno = iFreePage;
/* If pDbPage was a btree-page, then it may have child pages and/or cells
** that point to overflow pages. The pointer map entries for all these
** pages need to be changed.
**
** If pDbPage is an overflow page, then the first 4 bytes may store a
** pointer to a subsequent overflow page. If this is the case, then
** the pointer map needs to be updated for the subsequent overflow page.
*/
if( eType==PTRMAP_BTREE ){
rc = setChildPtrmaps(pDbPage);
if( rc!=SQLITE_OK ){
return rc;
}
}else{
Pgno nextOvfl = get4byte(pDbPage->aData);
if( nextOvfl!=0 ){
assert( nextOvfl<=sqlite3pager_pagecount(pPager) );
rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
if( rc!=SQLITE_OK ){
return rc;
}
}
}
/* Fix the database pointer on page iPtrPage that pointed at iDbPage so
** that it points at iFreePage. Also fix the pointer map entry for
** iPtrPage.
*/
rc = getPage(pBt, iPtrPage, &pPtrPage);
if( rc!=SQLITE_OK ){
return rc;
}
rc = sqlite3pager_write(pPtrPage->aData);
if( rc!=SQLITE_OK ){
releasePage(pPtrPage);
return rc;
}
modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
releasePage(pPtrPage);
return rc;
}
/* Forward declaration required by autoVacuumCommit(). */
static int allocatePage(Btree *, MemPage **, Pgno *, Pgno);
@@ -1624,10 +1697,8 @@ static int autoVacuumCommit(Btree *pBt){
u8 eType;
int pgsz = pBt->pageSize; /* Page size for this database */
Pgno iDbPage; /* The database page to move */
u8 *pDbPage = 0; /* "" */
MemPage *pDbMemPage = 0; /* "" */
Pgno iPtrPage; /* The page that contains a pointer to iDbPage */
MemPage *pPtrMemPage = 0; /* "" */
Pgno iFreePage; /* The free-list page to move iDbPage to */
MemPage *pFreeMemPage = 0; /* "" */
@@ -1685,7 +1756,6 @@ static int autoVacuumCommit(Btree *pBt){
}
rc = getPage(pBt, iDbPage, &pDbMemPage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
pDbPage = pDbMemPage->aData;
/* Find the next page in the free-list that is not already at the end
** of the file. A page can be pulled off the free list using the
@@ -1700,50 +1770,12 @@ static int autoVacuumCommit(Btree *pBt){
if( rc!=SQLITE_OK ) goto autovacuum_out;
assert( iFreePage<=origSize );
}while( iFreePage>finSize );
/* Move page iDbPage from it's current location to page number iFreePage */
TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
iDbPage, iFreePage, iPtrPage, eType));
releasePage(pFreeMemPage);
pFreeMemPage = 0;
rc = sqlite3pager_movepage(pPager, pDbPage, iFreePage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
pDbMemPage->pgno = iFreePage;
/* If pDbPage was a btree-page, then it may have child pages and/or cells
** that point to overflow pages. The pointer map entries for all these
** pages need to be changed.
**
** If pDbPage is an overflow page, then the first 4 bytes may store a
** pointer to a subsequent overflow page. If this is the case, then
** the pointer map needs to be updated for the subsequent overflow page.
*/
if( eType==PTRMAP_BTREE ){
rc = setChildPtrmaps(pDbMemPage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
}else{
Pgno nextOvfl = get4byte(pDbPage);
if( nextOvfl!=0 ){
assert( nextOvfl<=origSize );
rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
}
}
rc = relocatePage(pBt, pDbMemPage, eType, iPtrPage, iFreePage);
releasePage(pDbMemPage);
pDbMemPage = 0;
/* Fix the database pointer on page iPtrPage that pointed at iDbPage so
** that it points at iFreePage. Also fix the pointer map entry for
** iPtrPage.
*/
rc = getPage(pBt, iPtrPage, &pPtrMemPage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
rc = sqlite3pager_write(pPtrMemPage->aData);
if( rc!=SQLITE_OK ) goto autovacuum_out;
modifyPagePointer(pPtrMemPage, iDbPage, iFreePage, eType);
rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
releasePage(pPtrMemPage);
}
/* The entire free-list has been swapped to the end of the file. So
@@ -4198,6 +4230,7 @@ int sqlite3BtreeCreateTable(Btree *pBt, int *piTable, int flags){
MemPage *pRoot;
Pgno pgnoRoot;
int rc;
/* TODO: Disallow schema modifications if there are open cursors */
if( pBt->inTrans!=TRANS_WRITE ){
/* Must start a transaction first */
return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
@@ -4205,18 +4238,90 @@ int sqlite3BtreeCreateTable(Btree *pBt, int *piTable, int flags){
if( pBt->readOnly ){
return SQLITE_READONLY;
}
#ifdef SQLITE_OMIT_AUTOVACUUM
rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1);
if( rc ) return rc;
#ifndef SQLITE_OMIT_AUTOVACUUM
/* Note: This is temporary code for use during development of auto-vacuum.
** There should be no need for a pointer map entry for root-pages.
*/
#else
if( pBt->autoVacuum ){
rc = ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0);
if( rc ){
sqlite3pager_unref(pRoot->aData);
Pgno pgnoMove; /* Move a page here to make room for the root-page */
MemPage *pPageMove; /* The page to move to. */
/* Run the auto-vacuum code to ensure the free-list is empty. This is
** not really necessary, but it avoids complications in dealing with
** a free-list in the code below.
** TODO: This may need to be revisited.
*/
rc = autoVacuumCommit(pBt);
if( rc!=SQLITE_OK ) return rc;
/* Read the value of meta[3] from the database to determine where the
** root page of the new table should go. meta[3] is the largest root-page
** created so far, so the new root-page is (meta[3]+1).
*/
rc = sqlite3BtreeGetMeta(pBt, 4, &pgnoRoot);
if( rc!=SQLITE_OK ) return rc;
pgnoRoot++;
/* The new root-page may not be allocated on a pointer-map page. */
if( pgnoRoot==PTRMAP_PAGENO(pBt->pageSize, pgnoRoot) ){
pgnoRoot++;
}
assert( pgnoRoot>=3 );
/* Allocate a page. The page that currently resides at pgnoRoot will
** be moved to the allocated page (unless the allocated page happens
** to reside at pgnoRoot).
*/
rc = allocatePage(pBt, &pPageMove, &pgnoMove, 0);
if( rc!=SQLITE_OK ){
return rc;
}
if( pgnoMove!=pgnoRoot ){
u8 eType;
Pgno iPtrPage;
releasePage(pPageMove);
rc = getPage(pBt, pgnoRoot, &pRoot);
if( rc!=SQLITE_OK ){
return rc;
}
rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
if( rc!=SQLITE_OK ){
releasePage(pRoot);
return rc;
}
rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove);
releasePage(pRoot);
if( rc!=SQLITE_OK ){
return rc;
}
rc = getPage(pBt, pgnoRoot, &pRoot);
if( rc!=SQLITE_OK ){
return rc;
}
rc = sqlite3pager_write(pRoot->aData);
if( rc!=SQLITE_OK ){
releasePage(pRoot);
return rc;
}
}else{
pRoot = pPageMove;
}
rc = ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0);
if( rc ){
releasePage(pRoot);
return rc;
}
rc = sqlite3BtreeUpdateMeta(pBt, 4, pgnoRoot);
if( rc ){
releasePage(pRoot);
return rc;
}
}else{
rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1);
if( rc ) return rc;
}
#endif
assert( sqlite3pager_iswriteable(pRoot->aData) );
@@ -4307,6 +4412,7 @@ int sqlite3BtreeDropTable(Btree *pBt, int iTable){
int rc;
MemPage *pPage;
BtCursor *pCur;
/* TODO: Disallow schema modifications if there are open cursors */
if( pBt->inTrans!=TRANS_WRITE ){
return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
}
@@ -4351,7 +4457,9 @@ int sqlite3BtreeGetMeta(Btree *pBt, int idx, u32 *pMeta){
/* The current implementation is unable to handle writes to an autovacuumed
** database. So make such a database readonly. */
#ifdef SQLITE_OMIT_AUTOVACUUM
if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
#endif
return SQLITE_OK;
}