2012/1/6 Tom Lane <tgl@xxxxxxxxxxxxx>: > =?UTF-8?Q?Filip_Rembia=C5=82kowski?= <filip.rembialkowski@xxxxxxxxx> writes: >> Among following queries, only THREE runs fast enough for me. >> I can't understand the logic behind this. > > I'm not sure why you'd expect real answers when you haven't shown us > what the query is doing, it is an UDF, encapsulating a single SELECT where a=$1 and b=$2 and c=$3 > but my first thought is that the discrepancy > comes from additional buffer touches in the first execution of a query > in a given backend; which is not exactly surprising because that backend > has to load up its system catalog caches. IOW, the excess touches > represent accesses to system catalogs not user tables. > > In general, if you're annoyed by query execution times measured in > milliseconds, you'd be best advised not to start a fresh connection > for each one. A new connection not only involves a process launch > but a fair amount of loading of local caches, and a large part of > the latter work happens during the first few queries it processes. thank you, that explains a lot. I misinterpreted the number of buffer hits as true buffer reads. sure, using persistent connections is what I will do (we have pgbouncer here) Filip -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
