Re: EXPLAIN BUFFERS

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Euler Taveira de Oliveira <euler(at)timbira(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: EXPLAIN BUFFERS
Date: 2009-12-14 14:40:46
Message-ID: 28694.1260801646@sss.pgh.pa.us
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Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Pushing extra arguments around would create overhead of its own ...
>> overhead that would be paid even when not using EXPLAIN at all.

> I cannot understand what you mean... The additional argument should
> not be a performance overhead because the code path is run only once
> per execution.

Hmm, maybe, but still: once you have two flags you're likely to need
more. I concur with turning doInstrument into a bitmask as per Robert's
suggestion downthread.

regards, tom lane

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