Dan, The journal file contains the "before" image of a modified database block not the after image.
during write operations: before images are written to the journal file for recovery. Then the actual change is written to the .db file. A commit is an atomic operation due to unlinking the journal file. During recovery the journal file is played onto its corresponding .db file. This has the affect of a ROLLBACK command return the .db to a consistent state. So using the journal file to allow reads to continue is the correct place, given the current design of sqlite journalling and transactions. Dan Petitt <[EMAIL PROTECTED]> wrote: The journal file sounds like the wrong place to put it, the journal seems to be the place to store information that needs writing to the database on completion; storing some read-only information in the same file seems at odds with its current purpose. Perhaps a separate file(s) might be more appropriate to store this information, this might resolve your file format issues but also improve (but not eliminate) any performance considerations; perhaps the information could even (optionally) be stored in memory to greatly improve things. Dan -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: 30 October 2007 17:15 To: [email protected] Subject: Re: [sqlite] Your Concurrency Idea "Dan Petitt" wrote: > Richard, i noticed this ticket in the system: > http://www.sqlite.org/cvstrac/tktview?tn=2417,8 > > And wondered if its something that is getting any serious thought or > something that is just a faint possibility? > Seems to be an incompatibly file format change, which more or less rules it out for any consideration. Also unaddressed in the proposal is how to locate a particular page within the journal file without having to do (performance killing) sequential scan of the possible very large file. -- D. Richard Hipp ---------------------------------------------------------------------------- - To unsubscribe, send email to [EMAIL PROTECTED] ---------------------------------------------------------------------------- - ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
