On Wed, 20 Feb 2013 12:06:17 -0600 Seebs <se...@seebs.net> wrote: > On 20 Feb 2013, at 11:47, Simon Slavin wrote: > > > On 20 Feb 2013, at 5:32pm, Seebs <se...@seebs.net> wrote: > > > >> First: The SQL is completely trivial. > >> Second: I am not having performance problems with sqlite, I am having > >> performance problems with :memory:. Performance on files is lovely. > > > > This normally means that your computer has very little actual memory > > to devote to 'memory' uses. It is using a lot of swap space (or > > paging, or virtual memory, whatever you want to call it). So when you > > think you are doing calls which reference ':memory:' it actually has > > to fetch and write those parts of memory to disk. > > I am pretty sure that's not it. > > I know I'm a newbie on the list, but please imagine for the sake of > argument that I am a basically competent programmer with enough sysadmin > background to be aware of the obvious problems. > > In this case, I tested this pretty carefully over a period of about six > hours of testing across multiple machines. I was watching CPU load, > memory load, and all that stuff. And this is a machine with >4GB of > *free* memory -- that's over and above even the couple GB of disk cache > being used. > > Process memory size is not appreciably different between sqlite 3.6 and > 3.7, or between page size of 1024 or 8192. Runtime is massively > different. I am pretty sure this is an actual computation-time issue, > and my intuition is that it's quite possible there's at least some other > performance issues lurking, because it appears that :memory: *used to > be* dramatically faster than disk, but something changed in the last > couple of years.
The only thing i can think that explain it is compilation options, specifically SQLITE_TEMP_STORE=0. If you do pragma temp_store=2, does it work better? --- --- Eduardo Morras <emorr...@yahoo.es> _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
