Re: FW: REVIEW: Allow formatting in log_line_prefix

On Tue, Sep 24, 2013 at 5:04 AM, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
>> So... I guess the question that I'd ask is, if you write a PL/pgsql
>> function that does RAISE NOTICE in a loop a large number of times, can
>> you measure any difference in how fast that function executes on the
>> patch and unpatched code? If so, how much?
> I do see a 15-18% slow down with the patched version, so perhaps I'll need
> to look to see if I can speed it up a bit, although I do feel this benchmark
> is not quite a normal workload.

Ouch! That's pretty painful. I agree that's not a normal workload,
but I don't think it's an entirely unfair benchmark, either. There
certainly are people who suffer because of the cost of logging as
things are; for example, log_min_duration_statement is commonly used
and can produce massive amounts of output on a busy system.

I wouldn't mind too much if the slowdown you are seeing only occurred
when the feature is actually used, but taking a 15-18% hit on logging
even when the new formatting features aren't being used seems too
expensive to me.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company