Unfortunately I think that this would lock the whole database within SQLITE as there is no row level locking, so probably not the best way to go forward, unless all of the other applications are only performing reads ? Some othe ideas that might help. Have a field in one of your tables (May be a process table as Jim descriobed) that stores the last update time when your main app performed a refresh of the data. Your other applications could then infer that if that value is greater than some threshold that the data within is old and should not be trusted. So your other applications could infer from that that your app has crashed. In this case you might not need to clean the DB as the data is effectively implied as being bad given that the last_refresh time is outside of your accepted aging window. This assumes that you are periodically refreshing the data in there which sounds like that is the case On recovery (restart ) of your application I think the only thing you probably dont want to do is go thru the recreation of the tables as that would invalidate any prepares that your other applications have done. So may be delete the old data and refresh it (or simply overwrite it). In doing so your other applications would then see a new time stamp within the accepted threshold range and so could now trust that data again. Wayne
"Jim C. Nasby" <[EMAIL PROTECTED]> wrote: On Wed, Mar 01, 2006 at 07:38:58PM +0100, Elrond wrote: > > Hi, > > I'm considering to put the state of a running app into an > sqlite db. I want it in a db, so external tools can query > it and know, what the app is doing currently. > > Any hints on how to clean up the db, when the app crashes? > > (I have external resources, that I need to "lock", so the > idea is to put the locks in the db, so more than one > instance of the app can run and they don't kill the > external resource.) > > Any hints? Depending on your needs, you might be able to just lock a row for updates and hold that lock. IE, open a seperate connection to the database and do: BEGIN; UPDATE process SET start_time = now() WHERE process_id = ?; And then 'sit' on that connection until you're done. When you're finished, just issue a COMMIT. Note that some databases won't like you leaving that transaction open a real long time, so it depends on what you're doing if this will work. I also don't know if SQLite cares about such things. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
