On Sun, Jan 27, 2013 at 03:15:45AM +0300, belal hamed wrote: > > I connect to my server through ADSL connection 4Mbps >
Here is your "problem". You need to understand the performance characteristics of your communication channel. ADSL is a VERY asymmetric communications channel. Down is usually much faster than up. > I try this query > > select "MatID", "MatName", "MatCode" > from "Materials" > where "MatCode" ~* '^1101' > order by "MatCode" > limit 2 > > by wireshark I monitor TCP packets I found total data transmit/received 400B > I took about 2.5s to fetch results why ?????? > > after trying every solution mentioned in previous messages (DNS, tcpip, > postgresql.conf, ...) not found any improve, > > I tried this one: > > using Zebedee(http://www.winton.org.uk/zebedee/) > I build an IP tunnel between me and my data server (I used compression > level 9) > > surprisingly same query now took about 600 ms, "very impressive" > > same thing with this query > select "MatID", "MatName", "MatCode", "MatParent" from "Materials" > from 48s down to 17s > > all these tests done on same connection with same devices so same dns, > tcp-ip, .... > > now I am sure there is something wrong with libpq. When you wrap the communication channel in an IP tunnel, you are collapsing much of the syn-ack of the libpq protocol. You can see the same effect trying to run any sort of X windows application. Regards, Ken -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
