On 11/25/2010 08:49 PM, Simon Slavin wrote: > > On 25 Nov 2010, at 8:36am, Dan Kennedy wrote: > >> On 11/25/2010 03:24 PM, Twylite wrote: >>> > > Argh. Trevor, I'm going to find Stephenie Meyer and do something she doesn't > like. > >>> I am seeking technical information on the durability of transactions >>> with journal_mode=WAL and synchronous=NORMAL. >>> >>> Specifically, in the event of a power failure, can the following ever >>> happen: >>> (1) Loss of the last transaction completed. >>> (2) Loss of some indeterminate number of recent transactions. >>> (3) Loss of the entire WAL file. >>> (4) Corrupt of the database making it unopenable. >> >> Possible. Possible. Possible. Not supposed to be possible. > > Is (2) really possible ? I thought that, unless the power failure caused > corruption at the hard disk level, a maximum of one transaction could be lost. >
(2) and (3) are really the same question. In WAL mode with synchronous=NORMAL, when the user commits a transaction, it is written into the WAL file. No sync until a checkpoint happens. So if the power fails, you might lose all the transactions that have been written into the WAL file. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
