Re: SELECT constant; takes 15x longer on 9.0? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: SELECT constant; takes 15x longer on 9.0?
Date
Msg-id 20313.1270564136@sss.pgh.pa.us
Whole thread Raw
In response to SELECT constant; takes 15x longer on 9.0?  (Josh Berkus <josh@agliodbs.com>)
Responses Re: SELECT constant; takes 15x longer on 9.0?  ("David E. Wheeler" <david@kineticode.com>)
Re: SELECT constant; takes 15x longer on 9.0?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Josh Berkus <josh@agliodbs.com> writes:
> Continuing the performance test:

> DBD, like a number of monitoring systems, does "pings" on the database
> which look like this:

> SELECT 'DBD::Pg ping test';

> In our test, which does 5801 of these pings during the test, they take
> an average of 15x longer to execute on 9.0 as 8.4 ( 0.77ms vs. 0.05ms ).

There's something wrong with your test setup.  Or, if you'd like me to
think that there isn't, provide a self-contained test case.  I ran a
small program that does
for (i = 0; i < 10000; i++){    res = PQexec(conn, "SELECT 'DBD::Pg ping test'");    PQclear(res);}

and I only see a few percent difference between HEAD and 8.4.3,
on two different machines.  (It does appear that HEAD is a bit slower
for this, which might or might not be something to worry about.)
        regards, tom lane


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