I started to worry about this issue, because I am in a middle of an application development, and yesterday, it started to work, and I only SELECT a few times, and it makes a noticeable disk access. I'm still on magnetic HDD, but the application will be running on SSD or Flash drive.
Let me start again by a stupid question. If I do a SELECT... does this performs any disk write operation? I know that sqlite can store the database in RAM. Is there any way to (periodically) write the database to a regular sqlite file? Does sqlite calls 'sync()' after an UPDATE or INSERT? Thanks, Levente On Sat, 16 Aug 2014 22:22:56 +0100 Simon Slavin <slav...@bigfraud.org> wrote: > A good question. By which I mean it's one people should worry about, > not one which we're not sure about. > > No. Physical writes to Flash drives are optimized for best use of > hardware (minimum writes, promoting maximum lifetime for the device > and fastest execution of programs). Worse still, there is no > guarantee that any writes are done to the device at all until you > have issued 'unmount' to it (shown to the user as 'Eject' or 'Make > safe for removal' on popular popular operating systems). Until then, > as far as you're concerned, all the changes may be made only to a > cache held by the device driver. > > So if you pull your Flash drive without telling the OS to unmount it > you can get all sorts of problems, including no files at all if they > were created during that session. It's rare to see this actually > happen (few systems create a cache that reflects the whole drive then > never bother to flush it) but the specs of the hardware involved do > allow it. -- Levente Kovacs CTO, CSO http://levente.logonex.eu _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
