From: Mark Kirkwood <markir@paradise.net.nz>
To: Jim C. Nasby <jim@nasby.net>
Cc: Chris Browne <cbbrowne@acm.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Simple join optimized badly?
Date: Wed, 11 Oct 2006 13:34:53 +1300
Message-ID: <452C3C2D.6000008@paradise.net.nz> (raw)
In-Reply-To: <20061009211827.GL72517@nasby.net>
References: <45274A77.7080005@modgraph-usa.com>
<18722.1160236300@sss.pgh.pa.us>
<5f820f750610071850o6ed0b19o162d65d1987b2a8c@mail.gmail.com>
<200610081605.03501.josh@agliodbs.com>
<4529A0CA.8000904@modgraph-usa.com>
<4529B6D0.2010206@paradise.net.nz>
<4529B7E8.8080606@modgraph-usa.com>
<604pud8ise.fsf@dba2.int.libertyrms.com>
<20061009211827.GL72517@nasby.net>
Jim C. Nasby wrote:
> (snippage)... but we'll never get any progress so long as every
> time hints are brought up the response is that they're evil and should
> never be in the database. I'll also say that a very simple hinting
> language (ie: allowing you to specify access method for a table, and
> join methods) would go a huge way towards enabling app developers to get
> stuff done now while waiting for all these magical optimizer
> improvements that have been talked about for years.
It is possibly because some of us feel they are evil :-) (can't speak
for the *real* Pg developers, just my 2c here)
As for optimizer improvements well, yeah we all want those - but the
basic problem (as I think Tom stated) is the developer resources to do
them. As an aside this applies to hints as well - even if we have a
patch to start off with - look at how much time bitmap indexes have been
worked on to get them ready for release....
Personally I don't agree with the oft stated comment along the lines of
"we will never get the optimizer to the point where it does not need
some form of hinting" as:
1/ we don't know that to be a true statement, and
2/ it is kind of admitting defeat on a very interesting problem, when in
fact a great deal of progress has been made to date, obviously by people
who believe it is possible to build a "start enough" optimizer.
best wishes
Mark
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To: pgsql-performance@postgresql.org
Cc: markir@paradise.net.nz, jim@nasby.net, cbbrowne@acm.org
Subject: Re: Simple join optimized badly?
In-Reply-To: <452C3C2D.6000008@paradise.net.nz>
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