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Add the max_page_count pragma used to limit the maximum size of a database

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file.  Untested. (CVS 3948)

FossilOrigin-Name: b1b74f06688fd90fcaf54cf95e2e7beeb5fc1040
This commit is contained in:
drh
2007-05-08 14:51:36 +00:00
parent 17374e8f94
commit f8e632b630
9 changed files with 90 additions and 27 deletions
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31
src/pager.c
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@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.336 2007/05/05 11:48:54 drh Exp $
** @(#) $Id: pager.c,v 1.337 2007/05/08 14:51:37 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
@@ -256,9 +256,9 @@ struct Pager {
int nExtra; /* Add this many bytes to each in-memory page */
int pageSize; /* Number of bytes in a page */
int nPage; /* Total number of in-memory pages */
int nMaxPage; /* High water mark of nPage */
int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */
int mxPage; /* Maximum number of pages to hold in cache */
Pgno mxPgno; /* Maximum allowed size of the database */
u8 *aInJournal; /* One bit for each page in the database file */
u8 *aInStmt; /* One bit for each page in the database */
char *zFilename; /* Name of the database file */
@@ -1751,8 +1751,8 @@ int sqlite3PagerOpen(
/* pPager->stmtSize = 0; */
/* pPager->stmtJSize = 0; */
/* pPager->nPage = 0; */
/* pPager->nMaxPage = 0; */
pPager->mxPage = 100;
pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
assert( PAGER_UNLOCK==0 );
/* pPager->state = PAGER_UNLOCK; */
/* pPager->errMask = 0; */
@@ -1829,6 +1829,21 @@ int sqlite3PagerSetPagesize(Pager *pPager, int pageSize){
return pPager->pageSize;
}
/*
** Attempt to set the maximum database page count if mxPage is positive.
** Make no changes if mxPage is zero or negative. And never reduce the
** maximum page count below the current size of the database.
**
** Regardless of mxPage, return the current maximum page count.
*/
int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
if( mxPage>0 ){
pPager->mxPgno = mxPage;
}
sqlite3PagerPagecount(pPager);
return pPager->mxPgno;
}
/*
** The following set of routines are used to disable the simulated
** I/O error mechanism. These routines are used to avoid simulated
@@ -1914,6 +1929,9 @@ int sqlite3PagerPagecount(Pager *pPager){
if( n==(PENDING_BYTE/pPager->pageSize) ){
n++;
}
if( n>pPager->mxPgno ){
pPager->mxPgno = n;
}
return n;
}
@@ -2912,10 +2930,6 @@ static int pagerAllocatePage(Pager *pPager, PgHdr **ppPg){
pPg->pNextAll = pPager->pAll;
pPager->pAll = pPg;
pPager->nPage++;
if( pPager->nPage>pPager->nMaxPage ){
assert( pPager->nMaxPage==(pPager->nPage-1) );
pPager->nMaxPage++;
}
}else{
/* Recycle an existing page with a zero ref-count. */
rc = pager_recycle(pPager, 1, &pPg);
@@ -3060,6 +3074,9 @@ int sqlite3PagerAcquire(
** file, or by setting the entire page to zero.
*/
if( nMax<(int)pgno || MEMDB || (noContent && !pPager->alwaysRollback) ){
if( pgno>pPager->mxPgno ){
return SQLITE_FULL;
}
memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
pPg->needRead = noContent && !pPager->alwaysRollback;
IOTRACE(("ZERO %p %d\n", pPager, pgno));