Re: EXPLAIN BUFFERS

Euler Taveira <euler@timbira.com>

From: Euler Taveira de Oliveira <euler@timbira.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>, Greg Smith <greg@2ndquadrant.com>, Jeff Janes <jeff.janes@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2009-12-10T14:03:30Z
Lists: pgsql-hackers
Robert Haas escreveu:
> I'm not sure whether this is a good idea or not.  Let me read the
> patch.  I'm not sure an EXPLAIN option is really an adequate
> substitute for log_statement_stats - the latter will let you get stats
> for all of your queries automatically, I believe, and might still be
> useful as a quick and dirty tool.
> 
Why? If you want this information for all of your queries, you can always set
auto_explain.log_min_duration to 0. But if you're suggesting that we should
maintain log_statement_stats (that was not I understand from Tom's email [1]),
it's not that difficult to a change ShowBufferUsage().

> We certainly should NOT count on dtrace as a substitute for anything.
> It's not available on Windows, or all other platforms either.
> 
But we can always count on EXPLAIN BUFFERS. Remember that some monitoring
tasks are _only_ available via DTrace.

> I still think this is a bad format.  Instead of putting "(" and ")"
> around each phrase, can't we just separate them with a "," or ";"?
> 
We already use ( and ) to group things. I don't remember us using , or ; in
any output node. The suggested output is intuitive and similar to other nodes
patterns.


[1] http://archives.postgresql.org/pgsql-hackers/2009-10/msg00718.php


-- 
  Euler Taveira de Oliveira
  http://www.timbira.com/