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Added the new FULL option to the SYNCHRONOUS pragma. Still need to test it. (CVS 863)

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FossilOrigin-Name: 792a9e157dd066fcaffd4f5b373010151fb4ca61
This commit is contained in:
drh
2003-02-12 14:09:42 +00:00
parent d8d66e8ca0
commit 973b6e333d
11 changed files with 148 additions and 61 deletions
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38
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 1.74 2003/02/12 02:10:15 drh Exp $
** @(#) $Id: pager.c,v 1.75 2003/02/12 14:09:44 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -101,7 +101,7 @@ struct PgHdr {
u8 alwaysRollback; /* Disable dont_rollback() for this page */
PgHdr *pDirty; /* Dirty pages sorted by PgHdr.pgno */
/* SQLITE_PAGE_SIZE bytes of page data follow this header */
/* Pager.nExtra bytes of local data follow the page data and checksum */
/* Pager.nExtra bytes of local data follow the page data */
};
/*
@@ -470,10 +470,6 @@ static int pager_unwritelock(Pager *pPager){
*/
static u32 pager_cksum(Pager *pPager, Pgno pgno, const char *aData){
u32 cksum = pPager->cksumInit + pgno;
/* const u8 *a = (const u8*)aData;
int i;
for(i=0; i<SQLITE_PAGE_SIZE; i++){ cksum += a[i]; } */
/* fprintf(stderr,"CKSUM for %p(%08x) page %d: %08x\n", pPager, pPager->cksumInit, pgno, cksum); */
return cksum;
}
@@ -770,6 +766,36 @@ void sqlitepager_set_cachesize(Pager *pPager, int mxPage){
}
}
/*
** Adjust the robustness of the database to damage due to OS crashes
** or power failures by changing the number of syncs()s when writing
** the rollback journal. There are three levels:
**
** OFF sqliteOsSync() is never called. This is the default
** for temporary and transient files.
**
** NORMAL The journal is synced once before writes begin on the
** database. This is normally adequate protection, but
** it is theoretically possible, though very unlikely,
** that an inopertune power failure could leave the journal
** in a state which would cause damage to the database
** when it is rolled back.
**
** FULL The journal is synced twice before writes begin on the
** database (with some additional information being written
** in between the two syncs. If we assume that writing a
** single disk sector is atomic, then this mode provides
** assurance that the journal will not be corrupted to the
** point of causing damage to the database during rollback.
**
** Numeric values associated with these states are OFF==1, NORMAL=2,
** and FULL=3.
*/
void sqlitepager_set_safety_level(Pager *pPager, int level){
pPager->noSync = level==1 || pPager->tempFile;
pPager->fullSync = level==3 && !pPager->tempFile;
}
/*
** Open a temporary file. Write the name of the file into zName
** (zName must be at least SQLITE_TEMPNAME_SIZE bytes long.) Write