On Wed, Nov 30, 2011 at 1:39 PM, Teg <t...@djii.com> wrote: > Hello Richard, > > Appreciate the reply but, it doesn't address my question (unless I'm > missing something). I get that checkpointing doesn't reduce the size > of the WAL. Assuming a single writer and no readers, If I perform a > transaction that generates a WAL file. Does it eventually get deleted > when I finish my transaction? How about when I close the DB?
The wal file persists until the last connection to the database closes, then the wal file is deleted. Meanwhile, the wal file is recycled (meaning that SQLite starts reusing it again from the beginning) after each successful checkpoint. Checkpoints are automatically run by transactions that cause the size of the wal file to exceed 1000 pages (though this can be tuned or disabled if desired). For most applications, WAL mode just works and you don't have to think about how. > I haven't > updated to the most current SQlite because I was unclear about how > persistent the WAL files actually were. Some of my DB's are 30 GB+. I > don't mind the WAL's growing as long as they go away when the process > is finished. > > > > > > Wednesday, November 30, 2011, 1:10:50 PM, you wrote: > > RH> On Wed, Nov 30, 2011 at 1:04 PM, Teg <t...@djii.com> wrote: > > >> Hello Richard, > >> > >> When does the WAL get trimmed down? If my transaction completes, does > >> the WAL file get deleted? I've seen the WAL grow to 4 times my actual > >> DB size so, I don't really want 160 Gigs of WAL hanging out when the > >> process that generated it is only run once a month. > >> > > RH> SQLite starts writing the WAL file from the beginning again on the > first > RH> write transaction that follows a checkpoint that ran to completion and > RH> where there are no readers using the WAL file. A checkpoint will > normally > RH> run to completion if there are no readers still using prior > transactions. > RH> If there are readers on prior transactions, then the checkpoint cannot > run > RH> to completion since that would delete content out from under the > readers. > > > > > > > > -- > Best regards, > Teg mailto:t...@djii.com > > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
