On Fri, 2 Jul 2004, Chris Smith wrote: > I've just noticed in the regular profiling information from our web > application that a particular query on a fairly small database is taking about > 15 seconds. The query is generated from software on the fly, hence its > quirkiness -- if any of that is the problem, then I'll go ahead and fix it, > but I can't imagine a few repeated WHERE conditions fooling the query > optimizer. > > Anyway, I don't know how to interpret query plans. Can anyone give me a hand? > To get the plan, I just plugged in various values -- The actual query is run > with various different values, and even a few different lengths for the IN > clause. > > miqweb=> explain select distinct t0.* from UserAccount t0, UserMapping t1 > where > (t0.companyid = 123) and ((t0.companyid = 123) and (t0.userid = t1.userid) > and > (t1.groupid in (123, 234, 345, 456))) and (t0.companyid = 123);
Plain explain output is useful for finding what the plan is, but not as useful for determining why a query takes a particular amount of time. You might want to use "explain analyze" and send that result (which gives the real time and real number of rows for different steps). ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
