2010/2/6 Bret S. Lambert <bret.lambert@xxxxxxxxx>: > On Sat, Feb 06, 2010 at 02:44:32PM +0100, C?dric Villemain wrote: >> 2010/2/6 Bret S. Lambert <bret.lambert@xxxxxxxxx>: >> > On Fri, Feb 05, 2010 at 11:41:13PM +0200, Alexei Vladishev wrote: >> >> Greetings, >> >> >> >> Is there a way of configuring PostgreSQL so that one specific table would >> >> use, say, 4GB of buffer cache while other tables would use the rest? >> >> >> >> I would like to keep the table and its indexes always in "hot" >> >> state, so that >> >> other queries won't pollute this part of the buffer cache. It would ensure >> >> reliable performance and much less disk IOPS working with the table. >> > >> > Fiddling with the buffer cache like that would require some sort of >> > OS support, if I'm not mistaken in what you're asking for. >> > >> > And then, even if the support is there, you'd need to outline exactly >> > how you're planning on pushing this button. >> > >> > Specifically, what's your usage pattern that would make this a >> > win for you? >> > >> > If the table and its indexes can already fit into the buffer cache, >> > and it's as commonly accessed as you think it is, the OS should >> > probably have it cached anyway. >> >> that's all true. >> >> I am working on pgfincore which allow in some way to prepare buffer cache. >> You need pg > 8.4 and linux (probably working with bsd too) > > Why do something with a non-portable interface? Most OSes support > coherently mmap(2)'ing disk blocks into memory; in fact, I'm somewhat > taken aback that the postgres buffer cache isn't implemented in that > manner, but I'm willing to give the devs credit for having not done > so for good reasons. currrently, pgfincore is implement via mmap'ing and mincore. This is the mincore implementation which might differ. In next release there will probably a system call 'fincore()' which is probably going to be integrated in linux kernel. Doing all of those in a portable way is not fully possible (thinks windows), but it may be possible using #ifdef things to catch the good system call for each OS (if possible/implemented). > >> >> I don't consider it ready fo rproduction, but fine for debugging >> things, if you reall care the buffer cache preload, tell me, I'll >> stabilize the code in a shorter time ;) >> http://villemain.org/projects/pgfincore >> >> > >> >> >> >> Is it possible? >> >> >> >> Thanks for any hints! >> >> >> >> Alexei >> >> >> >> -- >> >> Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) >> >> To make changes to your subscription: >> >> http://www.postgresql.org/mailpref/pgsql-general >> > >> > -- >> > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) >> > To make changes to your subscription: >> > http://www.postgresql.org/mailpref/pgsql-general >> > >> >> >> >> -- >> C?dric Villemain > -- Cédric Villemain -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
