Skip site navigation (1) Skip section navigation (2)

Re: Auto-explain patch

From: Dean Rasheed <dean_rasheed(at)hotmail(dot)com>
To: Alex Hunsaker <badalex(at)gmail(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Auto-explain patch
Date: 2008-07-03 16:58:07
Message-ID: BAY102-W42AF4FE40B20BE3C18EE73F2980@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-hackers
Here is an updated version of the patch, with a debug_explain_min_duration
parameter to allow explaining of just slow-running queries. I've also incorporated
a couple of Simon Riggs' suggestions for formatting the output better.

Do I need to post this to -patches, or is that now obsolete?

Regards, Dean

----------------------------------------
> From: dean_rasheed(at)hotmail(dot)com
> To: badalex(at)gmail(dot)com
> CC: pgsql-hackers(at)postgresql(dot)org
> Subject: RE: [HACKERS] Auto-explain patch
> Date: Wed, 2 Jul 2008 19:42:06 +0000
>
>
>> Its certainly not useful to *me* in its current form. It would
>> produce way to much (usless) output. However if it were tied to
>> log_min_duration_statement so I get auto explains for long running
>> queries... That would be very useful indeed. Even if it has to
>> explain everything just to toss out the explain if it did not meet
>> log_min_duration_statement. Unless I missed something and thats
>> exactly what it does?
>
> Thanks for the feedback. I agree, it does need a way to limit the
> output, and target just the slow-running queries.
>
> I also remember now the problem I had last time:- since this debug
> output is produced at a lower level than the other statement logging
> (so it can explain *all* SQL executed, not just top-level statements), it
> is difficult to control using the normal statement logging parameters.
>
> It would be easy to add another parameter, debug_explain_min_duration,
> specific to this option, to limit it to slow low-level queries.
>
> This would allow setting debug_explain_min_duration to be smaller than
> log_min_duration_statement, which makes sense, since the latter
> controls logging of top-level statements which may result in multiple
> low-level queries.
>
> Doing it this way would mean instrumenting all queries, but only
> explaining the slow ones, when debug_explain_plan is on.
> I'll have a play and see how it goes...
>
> Regards, Dean
>
> _________________________________________________________________
> Live Search Charades - guess correctly and find hidden videos
> http://www.searchcharades.com/

_________________________________________________________________
The next generation of Windows Live is here
http://www.windowslive.co.uk/get-live

Attachment: auto-explain2.patch
Description: text/x-patch (13.1 KB)

Responses

pgsql-hackers by date

Next:From: Mark MielkeDate: 2008-07-03 17:18:19
Subject: Re: A Windows x64 port of PostgreSQL
Previous:From: Alvaro HerreraDate: 2008-07-03 16:53:15
Subject: Re: PATCH: CITEXT 2.0

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group