Re: Slow query execution over WAN network

Clemens Eisserer <linuxhippy(at)gmail(dot)com> Thursday 24 February 2011 15:56:10
> Hi,
>
> I experience really slow query execution over remote networks,
> especially for a query which returns a lot of columns (~255) caused by
> joins.
>
> Executing the same query over different networks gives the following times:
> Local: 20ms
> DSL: 400ms
> UMTS: 1500ms
>
> The query returns 12 rows, and 255 column - most of them with only
> very little data. A wireshark-snapshot of a request is only ~30kb
> large, so I guess there isn't a lot of data transported.
>
> I've uploaded a netbeans-profiler screenshot as well as a wireshark profile
> to: http://93.190.88.182/jdbc_traffic.wireshark
> http://93.190.88.182/jdbc_profile.png
>
> Any idea whats causing the high latency? Are there multiple
> round-trips going on here?
> I already tried adjusting fetch size, however didn't change anything.
>
> Thank you in advance, Clemens
>
> PS: I've asked the question already on pgsql-performance,
> unfourtunatly there wasn't a lot of feedback. Sorry for cross-posting.
Hi,

You truncated times in profiler window. May I ask what time was measured for
socket.read(), and what kind of connection did you used for this (dsl, umts),
connection speed and min/max/avg ping time to database server?

What other operations are performed inside benchamrkQuery(), commit/rollback,
connection open?
Did fetch size wa,s when you was making this test, enaught to get all records
at once?

It is highly probable that something is wrong.

Regards,
Radek