From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: That EXPLAIN ANALYZE patch still needs work |
Date: | 2006-06-09 10:11:51 |
Message-ID: | 1149847912.2691.240.camel@localhost.localdomain |
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Lists: | pgsql-hackers |
On Thu, 2006-06-08 at 17:21 -0400, Tom Lane wrote:
> Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> > Tried on two machines. The first (Turion64 laptop) gives 44-45 ms for
> > the SELECT, and 50-51 ms for the EXPLAIN ANALYZE.
>
> > The second machine, desktop Celeron 533, gives 197-200 ms for the SELECT
> > and 788-790 for the EXPLAIN ANALYZE. I guess this is the reproduction
> > you were looking for.
>
> Do you have oprofile installed on these? Comparing oprofile results
> might give some more insight where the time is going.
On my office PC the overhead from EA is about 20%.
stracing a backend, I also notice that on a 1.5 million row table we
make only 39158 calls to gettimeofday, on a table of 24591 blocks.
I'm thinking that the instrumentation overhead has been reduced as a
result of the page-at-a-time heap scans we now have?
--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com
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