Re: SELECT constant; takes 15x longer on 9.0?

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