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Avoid creating a master journal unless two or more databases in the

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transaction can actually benefit from that master journal.

FossilOrigin-Name: 3ed1890612bd45bd9c72f670d2cbb0b8fbd35d92
This commit is contained in:
drh
2016-02-22 14:57:38 +00:00
parent e872d5133d
commit 8e6cf0a7c5
4 changed files with 105 additions and 29 deletions
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26
src/vdbeaux.c
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@@ -2155,7 +2155,9 @@ int sqlite3VdbeSetColName(
*/
static int vdbeCommit(sqlite3 *db, Vdbe *p){
int i;
int nTrans = 0; /* Number of databases with an active write-transaction */
int nTrans = 0; /* Number of databases with an active write-transaction
** that are candidates for a two-phase commit using a
** master-journal */
int rc = SQLITE_OK;
int needXcommit = 0;
@@ -2183,10 +2185,28 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
Btree *pBt = db->aDb[i].pBt;
if( sqlite3BtreeIsInTrans(pBt) ){
/* Whether or not a database might need a master journal depends upon
** its journal mode (among other things). This matrix determines which
** journal modes use a master journal and which do not */
static const u8 aMJNeeded[] = {
/* DELETE */ 1,
/* PERSIST */ 1,
/* OFF */ 0,
/* TRUNCATE */ 1,
/* MEMORY */ 0,
/* WAL */ 0
};
Pager *pPager; /* Pager associated with pBt */
needXcommit = 1;
if( i!=1 ) nTrans++;
sqlite3BtreeEnter(pBt);
rc = sqlite3PagerExclusiveLock(sqlite3BtreePager(pBt));
pPager = sqlite3BtreePager(pBt);
if( db->aDb[i].safety_level!=PAGER_SYNCHRONOUS_OFF
&& aMJNeeded[sqlite3PagerGetJournalMode(pPager)]
){
assert( i!=1 );
nTrans++;
}
rc = sqlite3PagerExclusiveLock(pPager);
sqlite3BtreeLeave(pBt);
}
}