On Wed, Aug 10, 2011 at 1:09 PM, Simon Slavin <slav...@bigfraud.org> wrote:
> > On 10 Aug 2011, at 6:01pm, Sreekumar TP wrote: > > > Thanks for the explanation. The journal mode was OFF which means there > is > > no journal file created. So why is it the check still performed ? > > Because the journal mode might have been 'ON' the last time that database > was used. > More importantly, the journal mode might be 'ON' in the other process that crashed in the middle of a transaction. > > > On Wed, Aug 10, 2011 at 10:24 PM, Richard Hipp <d...@sqlite.org> wrote: > > > >> On Wed, Aug 10, 2011 at 12:40 PM, Sreekumar TP <sreekumar...@gmail.com > >>> wrote: > >> > >>> The 179148 failures on 'access' system call is due to access check of > two > >>> files - the journal file and the wal-file. > > Well, the file is obviously not being opened 179148 times. I thought it > checked for these files only when sqlite3_open() was being run. Is it > checking for these files every time a command is executed ? Surely that is > unnecessary and a source of a large reduction in speed. > SQLite must check for hot journals at the start of each transaction. Or, more precisely, SQLite must check for hot journals whenever it starts reading the database again after a period of time when another process might have been writing to the database (and might have crashed while writing). That's when PRAGMA locking_mode=EXCLUSIVE blocks the hot-journal checks. If your process has exclusive access to the database, it is not possible for another process to write to the database (and crash in the middle of writing). > > Simon. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
