On Wed, Dec 30, 2009 at 4:31 PM, Joshua D. Drake <j...@commandprompt.com> wrote: > On the other hand ANALYZE also: > > 1. Uses lots of memory > 2. Lots of processor > 3. Can take a long time > > We normally don't notice because most sets won't incur a penalty. We got a > customer who > has a single table that is over 1TB in size... We notice. Granted that is > the extreme > but it would only take a quarter of that size (which is common) to start > seeing issues.
I'm a bit puzzled by people's repeated suggestion here that large tables take a long time to analyze. The sample analyze takes to generate statistics is not heavily influenced by the size of the table. Your 1TB table should take basically the same amount of time as a 1GB table or a 1MB table (if it wasn't already in cache). Unless the reason why it's 1TB is that the columns are extremely wide rather than that it has a lot of rows? Or unless you've raised the statistics target in (a misguided*) belief that larger tables require larger statistics targets to achieve the same level of accuracy. Or unless when you say "ANALYZE" you're really running "VACUUM ANALYZE". [*] except for ndistinct estimates :( -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
