Part of my app will, at user request, read some data from an SQLite db and also some files from disk, and send it all out on the network. This may in some cases take several minutes, at the end of which the db gets updated here and there. While this is happening, the user may wish to do another action that will require read/write access to this db. Typically this will be another process.
As it happens I'd not tried exactly the above until yesterday, at which point I got "database locked" after my timeout period expired. Although I'm careful to finalize() and close() as appropriate, the way things are structured at present the database is left open while the slow processing (writing to the network) takes place. I can rejig this without too much trouble, but for various reasons it's not just a simple case of "closing the db earlier", and so I'd like to be sure I understand how things work before starting. I'm using PHP's sqlite3 class rather than PDO, and I've done nothing explicit about the journal mode. My questions are: 1) I start with $dbh = new sqlite3 ($dbname); Am I right in thinking that this does not explicitly open the db (and hence acquire a lock), but that the db is opened and the default lock (SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE) is acquired only when the first query is done? 2) If I want to use a different flag such as SQLITE_OPEN_READONLY do I need to do an explicit open such as $dbh->open ($dbname, SQLITE_OPEN_READONLY); or is there a way to specify the flag(s) with "new sqlite3" ? 3) Is the lock always released if I do $dbh->close(); ? 4) Would it just be simpler to switch to WAL mode? My rejigging would involve closing db's when I'm about to do something potentially slow and then and re-opening them later but I don't think that would cause significant overhead. -- Cheers -- Tim
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