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Make sure the pagers in-memory cache states in sync with the disk file.

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Ticket #529. (CVS 1133)

FossilOrigin-Name: da00efb13fe8ccf1c27e4e1193df6b53de9463f4
This commit is contained in:
drh
2003-12-17 23:57:34 +00:00
parent 4be295be07
commit acf4ac96e3
5 changed files with 91 additions and 23 deletions
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22
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 1.90 2003/09/06 01:10:47 drh Exp $
** @(#) $Id: pager.c,v 1.91 2003/12/17 23:57:35 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -520,19 +520,13 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int format){
sqliteOsSeek(&pPager->fd, (pgRec.pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, pgRec.aData, SQLITE_PAGE_SIZE);
if( pPg ){
if( pPg->nRef==0 ||
memcmp(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE)==0
){
/* Do not update the data on this page if the page is in use
** and the page has never been modified. This avoids resetting
** the "extra" data. That in turn avoids invalidating BTree cursors
** in trees that have never been modified. The end result is that
** you can have a SELECT going on in one table and ROLLBACK changes
** to a different table and the SELECT is unaffected by the ROLLBACK.
*/
memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE);
memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
}
/* No page should ever be rolled back that is in use, except for page
** 1 which is held in use in order to keep the lock on the database
** active.
*/
assert( pPg->nRef==0 || pPg->pgno==1 );
memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE);
memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
pPg->dirty = 0;
pPg->needSync = 0;
}