Re: Timing of 'SELECT 1'

From: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
To: "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: "PostgreSQL-development" <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: Timing of 'SELECT 1'
Date: 2004-03-10 15:00:55
Message-ID: 6EE64EF3AB31D5448D0007DD34EEB34101AD85@Herge.rcsinc.local
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Bruce Momjian wrote:
> I am timing small queries, and found that a PREPARE/EXECUTE of "SELECT
> 1" takes about 1.2ms on my machine. A normal SELECT doesn't take much
> longer, so I am wondering why a simpler query isn't faster.
>
> Looking at log_executor_stats, I see the following. Execute shows
> nothing taking much time, mostly < .2ms, but the total seems high. I
> wonder if one of our standard query start/stop functions is taking too
> long and can be optimized.

There seems to be a 'PostgreSQL ping' time of about 1-2 ms in best case
conditions which limits the amount of queries you can fire off in 1
second, no matter how simple. In certain rare cases this is something
of a bottleneck. In my personal case it would be nice to see that time
lower because converted COBOL applications tend to generate a lot of
'simple' queries.

Merlin

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