Date: Wed, 11 Oct 2006 13:34:53 +1300
From: Mark Kirkwood <markir@paradise.net.nz>
Subject: Re: Simple join optimized badly?
In-reply-to: <20061009211827.GL72517@nasby.net>
To: "Jim C. Nasby" <jim@nasby.net>
Cc: Chris Browne <cbbrowne@acm.org>, pgsql-performance@postgresql.org
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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