From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Smith <greg@2ndQuadrant.com>
cc: pgsql-docs <pgsql-docs@postgresql.org>
Subject: Re: Clarify TIMING OFF behavior
In-reply-to: <51985D31.1030705@2ndQuadrant.com>
References: <51985D31.1030705@2ndQuadrant.com>
Comments: In-reply-to Greg Smith <greg@2ndQuadrant.com>
	message dated "Sun, 19 May 2013 01:03:45 -0400"
Date: Sun, 19 May 2013 22:06:20 -0400
Message-ID: <13411.1369015580@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-docs-owner@postgresql.org

Greg Smith <greg@2ndQuadrant.com> writes:
> While chatting in #pedant today, I noticed that it's not clear that 
> EXPLAIN (ANALYZE ON, TIMING OFF) will still collect the total runtime of 
> the statement.  Attached patch clarifies that.  It also comments why the 
> related code runs INSTR_TIME_SET_CURRENT in all cases.  That's actually 
> how I noticed that--a read through explain.c now could rightly wonder 
> "why is it still collecting that bit of time info when TIMING is off?"

Applied with a little bit of further wordsmithing.

> There's an argument possible here that a third TIMING option besides 
> ON/OFF should really exist, one that really doesn't do any timing at 
> all.  I don't think enough use cases for that exist to justify coding 
> it.

Agreed.  If you can't tolerate two gettimeofday calls per EXPLAIN,
you don't need a new EXPLAIN option ... you need new hardware.

			regards, tom lane


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