Message-ID: <4D4B2740.3070902@agliodbs.com>
Date: Thu, 03 Feb 2011 14:08:00 -0800
From: Josh Berkus <josh@agliodbs.com>
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To: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] Slow count(*) again...
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On 2/3/11 1:18 PM, Chris Browne wrote:
> mladen.gogala@vmsinfo.com (Mladen Gogala) writes:
>> I must say that this purist attitude is extremely surprising to
>> me. All the major DB vendors support optimizer hints,

I don't think that's actually accurate.  Can you give me a list of
DBMSes which support hints other than Oracle?

> Well, the community declines to add hints until there is actual
> consensus on a good way to add hints.
> 
> Nobody has ever proposed a way to add hints where consensus was arrived
> at that the way was good, so...

Well, we did actually have some pretty good proposals (IIRC) for
selectively adjusting the cost model to take into account DBA knowledge.
 These needed some refinement, but in general seem like the right way to go.

However, since this system wasn't directly compatible with Oracle Hints,
folks pushing for hints dropped the solution as unsatisfactory. This is
the discussion we have every time: the users who want hints specifically
want hints which work exactly like Oracle's, and aren't interested in a
system designed for PostgreSQL.  It's gotten very boring; it's like the
requests to support MySQL-only syntax.

-- 
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com