Phoenix Kiula escribió: > On 03/09/07, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > > "Phoenix Kiula" <phoenix.kiula@xxxxxxxxx> writes: > > > most_common_vals will (and should) be empty if there aren't actually any > > common values, but aren't you getting a histogram? Exactly what > > performance do you think will be improved? > > > Lots of posts here in reponse to performance question have the > recommendation "increase the stats on that column". From whatever > succint reading is made available on the postgres site, I gather that > this aids the planner in getting some info about some of the data. Am > I missing something here, or totally off-base? > > The issue is that I don't quite get why MySQL can fetch one indexed > row (i.e., SQL that ends with a very simple "WHERE indexed_column = > 'constant' ") in a matter of milliseconds, but PgSQL is taking 5 to 6 > seconds on an average at least for the first time. I use RAPTOR 15K > drives, they're not SCSI but they're not exactly "cheap disks" either. > And I have 4GB RAM. The explain select shows that index is being > used! Let's see the explain output? I doubt your games with stats have anything to do with it. Maybe it is having to scan a lot of dead tuples or something like that. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
