Thanks :) This did the trick: First make a copy of the database: copy HugeDatabase.db HugeDatabase_copy.db Then for each run, replace the database with its copy. This is why I thought the COUNT operation was somehow written to the database after its first run... :P
> From: slav...@bigfraud.org > Date: Mon, 21 Feb 2011 16:56:01 +0000 > To: sqlite-users@sqlite.org > Subject: Re: [sqlite] COUNT() extremely slow first time! > > > On 21 Feb 2011, at 4:35pm, Jim Wilcoxson wrote: > > > On Mon, Feb 21, 2011 at 11:05 AM, Sven L <larvpo...@hotmail.se> wrote: > >> > >> Thank you for your detailed explanation! > >> First, can you please tell me how to purge the cache in Windows 7? This > >> could be very useful for my tests! > > > > Sorry, dunno for Windows. On Mac OSX it is the purge command, in the > > development tools. > > In current versions it's just /usr/bin/purge/, which should be in your path. > No idea why a non-programmer should need it, but there it is. > > > On Linux, you do: echo 3 > > > /prog/sys/vm/drop_caches > > And in Windows it's ... almost impossible. You can sync to disk, using > fflush(), and there's no reason you can't do this from the command-line: > > http://technet.microsoft.com/en-us/sysinternals/bb897438.aspx > > But for a purge you have to invalidate the contents of cache, and there's no > way for an application to tell Windows to do this. For a start, each > application has its own user mode address cache, so if you run another > utility to flush cache, it just messes with its own space. Second, there's no > system call that allows you access to the cache because Microsoft considers > it private to the device level. I am not dissing Microsoft for this: there > are fair arguments that this is actually the Right Way to do it. > > So the way to do it is to overrun the cache by yourself. If you know your > cache is 2Gig, find a 2Gig disk file that has nothing to do with your test > suite and read it. Or generate 2Gig of gibberish and write it to disk, then > delete that file. Pah. > > Simon. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
