Обсуждение: Re: Slow "Select count(*) ..." query on table with 60 Mio. rows
Matthew Wakeling <matthew@flymine.org> wrote: > This is an FAQ. I just added it to the wiki FAQ page: http://wiki.postgresql.org/wiki/FAQ#Why_is_.22SELECT_count.28.2A.29_FROM_bigtable.3B.22_slow.3F -Kevin
Kevin Grittner wrote: > Matthew Wakeling <matthew@flymine.org> wrote: > >> This is an FAQ. > > I just added it to the wiki FAQ page: > > http://wiki.postgresql.org/wiki/FAQ#Why_is_.22SELECT_count.28.2A.29_FROM_bigtable.3B.22_slow.3F Maybe you could add a short note why an estimation like from the pg_class table is usually enough.
Ivan Voras <ivoras@freebsd.org> wrote: > Maybe you could add a short note why an estimation like from the > pg_class table is usually enough. OK. Will do. -Kevin
Kevin Grittner wrote:
The content was already there, just not linked into the main FAQ yet: http://wiki.postgresql.org/wiki/Slow_CountingMatthew Wakeling <matthew@flymine.org> wrote:This is an FAQ.I just added it to the wiki FAQ page: http://wiki.postgresql.org/wiki/FAQ#Why_is_.22SELECT_count.28.2A.29_FROM_bigtable.3B.22_slow.3F
-- Greg Smith 2ndQuadrant Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.com
Greg Smith <greg@2ndquadrant.com> wrote: > The content was already there, just not linked into the main FAQ > yet: > http://wiki.postgresql.org/wiki/Slow_Counting For a question asked this frequently, it should probably be in the FAQ. I'll add a link from there to the more thorough write-up. -Kevin
Kevin Grittner wrote:
There's a whole list of FAQs that are documented on the wiki but not in the main FAQ yet leftover from before the main FAQ was hosted there. You can see them all at http://wiki.postgresql.org/wiki/Frequently_Asked_Questions
I just haven't had time to merge those all usefully into the main FAQ.
Greg Smith <greg@2ndquadrant.com> wrote:The content was already there, just not linked into the main FAQ yet: http://wiki.postgresql.org/wiki/Slow_CountingFor a question asked this frequently, it should probably be in the FAQ. I'll add a link from there to the more thorough write-up.
There's a whole list of FAQs that are documented on the wiki but not in the main FAQ yet leftover from before the main FAQ was hosted there. You can see them all at http://wiki.postgresql.org/wiki/Frequently_Asked_Questions
I just haven't had time to merge those all usefully into the main FAQ.
-- Greg Smith 2ndQuadrant Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.com
Greg Smith <greg@2ndquadrant.com> wrote: > There's a whole list of FAQs that are documented on the wiki but > not in the main FAQ yet leftover from before the main FAQ was > hosted there. You can see them all at > http://wiki.postgresql.org/wiki/Frequently_Asked_Questions > > I just haven't had time to merge those all usefully into the main > FAQ. Well, unless you object to the way I did it, there's one down. Should I remove it from the list of "Other FAQs" on the page you cite? (Of course, it goes without saying that you're welcome to improve upon anything I put in there.) -Kevin
Kevin Grittner wrote:
Sure; everyone should feel free to assimilate into the main FAQ and wipe out anything on that smaller list. Those are mainly topics where the discussion of workarounds and approaches can be much longer than standard FAQ length, so I suspect many of the answers are going to be a very brief summary with a link to longer discussion. If you come across a really small one, we might even wipe out the original page once it's merged in.
Greg Smith <greg@2ndquadrant.com> wrote:There's a whole list of FAQs that are documented on the wiki but not in the main FAQ yet leftover from before the main FAQ was hosted there. You can see them all at http://wiki.postgresql.org/wiki/Frequently_Asked_Questions I just haven't had time to merge those all usefully into the main FAQ.Well, unless you object to the way I did it, there's one down. Should I remove it from the list of "Other FAQs" on the page you cite?
Sure; everyone should feel free to assimilate into the main FAQ and wipe out anything on that smaller list. Those are mainly topics where the discussion of workarounds and approaches can be much longer than standard FAQ length, so I suspect many of the answers are going to be a very brief summary with a link to longer discussion. If you come across a really small one, we might even wipe out the original page once it's merged in.
-- Greg Smith 2ndQuadrant Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.com