diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/pager.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/src/pager.c b/src/pager.c index 67b95f718..2230174e5 100644 --- a/src/pager.c +++ b/src/pager.c @@ -647,6 +647,7 @@ struct Pager { u8 doNotSpill; /* Do not spill the cache when non-zero */ u8 subjInMemory; /* True to use in-memory sub-journals */ u8 bUseFetch; /* True to use xFetch() */ + u8 hasBeenUsed; /* True if any content previously read from this pager*/ Pgno dbSize; /* Number of pages in the database */ Pgno dbOrigSize; /* dbSize before the current transaction */ Pgno dbFileSize; /* Number of pages in the database file */ @@ -3897,7 +3898,7 @@ static int pagerAcquireMapPage( PgHdr **ppPage /* OUT: Acquired page object */ ){ PgHdr *p; /* Memory mapped page to return */ - + if( pPager->pMmapFreelist ){ *ppPage = p = pPager->pMmapFreelist; pPager->pMmapFreelist = p->pDirty; @@ -5128,16 +5129,12 @@ int sqlite3PagerSharedLock(Pager *pPager){ ); } - if( !pPager->tempFile && ( - pPager->pBackup - || sqlite3PcachePagecount(pPager->pPCache)>0 - || USEFETCH(pPager) - )){ - /* The shared-lock has just been acquired on the database file - ** and there are already pages in the cache (from a previous - ** read or write transaction). Check to see if the database - ** has been modified. If the database has changed, flush the - ** cache. + if( !pPager->tempFile && pPager->hasBeenUsed ){ + /* The shared-lock has just been acquired then check to + ** see if the database has been modified. If the database has changed, + ** flush the cache. The pPager->hasBeenUsed flag prevents this from + ** occurring on the very first access to a file, in order to save a + ** single unnecessary sqlite3OsRead() call at the start-up. ** ** Database changes is detected by looking at 15 bytes beginning ** at offset 24 into the file. The first 4 of these 16 bytes are @@ -5302,6 +5299,7 @@ int sqlite3PagerAcquire( if( pgno==0 ){ return SQLITE_CORRUPT_BKPT; } + pPager->hasBeenUsed = 1; /* If the pager is in the error state, return an error immediately. ** Otherwise, request the page from the PCache layer. */ @@ -5451,6 +5449,7 @@ DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){ assert( pgno!=0 ); assert( pPager->pPCache!=0 ); pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0); + assert( pPage==0 || pPager->hasBeenUsed ); return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage); } |