On Jul 28, 2006, at 3:15 PM, Dirk Stoop wrote: > Hi Everybody, > > We're writing a Mac OS X app which uses an SQLite data store through > sqlobject. > > I'm tuning the app for better performance and found that setting: > "PRAGMA synchronous = OFF" > improves performance dramatically, which is to be expected if you > read the description found on http://sqlite.org/pragma.html > > Since we're running this app on a journaled file system, and SQLite > keeps a journal of everything it hasn't written to the database yet, > it seems to me that it's not necessary to let SQLite check for every > transaction if it's actually written to disk. > > Does any of you have any experience with using SQLite files with > "PRAGMA synchronous = off" on a journaled filesystem? > > Could you offer me any clue about the kind of trade-off I'm making?
You might loose data. The journal on HFS+ is a meta-data journal, it ensures that the metadata (such as the mtime of files and administratration about which blocks are in use) can be made correctly after a crash without a full check of the filesystem, but doesn't guarantee that the contents of files is correct. One way you might notice the difference is when you append data to a file, if a crash happens you might end up with a file that has already been extended (blocks allocated and file size updated), but doesn't actually contain the data your wrote to it (but NUL bytes instead). Ronald ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ sqlobject-discuss mailing list sqlobject-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss
