On 22.10.2013 06:49, Magnus Hagander wrote: > > On Oct 22, 2013 1:14 AM, "Tomas Vondra" <tv@xxxxxxxx > <mailto:tv@xxxxxxxx>> wrote: >> >> On 22.10.2013 00:59, sparikh wrote: >> > Yes, Expalin without Analyze is taking long. It is weird. In the >> > pg_stat_activity Explain was the only query running. So server was >> > almost idle. Using New relic interface I checked CPU was almost idle >> > - around 10-20%. There were some IO activity - around 40-50%. >> > >> > I forgot to mention before I could run perf on command line even with >> > root permission. It says command not found. May be utility is not >> > installed or not enabled. >> >> Obviously you need to install it ... maybe ask your sysadmin to do that. >> >> > I have attached the snapshot of vmstat while explain was running in >> > background. vmstat.txt >> > <http://postgresql.1045698.n5.nabble.com/file/n5775349/vmstat.txt> >> >> The vmstat clearly shows that ~1 CPU is waiting on I/O. Hmm, I'm really >> wondering what's going on here - I can't think of a case where this >> would happen with a plain EXPLAIN ... > > Catalog bloat could make that happen. Though that should show up on > the master as well, it could be that it's cached there and therefor > only shows us to as cpu and not io and is therefore not noticed. Maybe, but sparikh reported the query to be running for ~20 minutes. That'd be hell of a bloat. Sparikh, can you show us the size of system catalogs? Something like SELECT relname, relpages FROM pg_class WHERE relname LIKE 'pg%' ORDER BY relpages DESC LIMIT 20; Should give the same results both on primary and standby. Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
