User-Agent: Microsoft-Entourage/11.2.5.060620
Date: Sun, 23 Jul 2006 23:23:48 -0700
Subject: Re: On-disk bitmap index patch
From: "Jie Zhang" <jzhang@greenplum.com>
To: "Gavin Sherry" <swm@linuxworld.com.au>,
	"Tom Lane" <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org,
	"Luke Lonergan" <LLonergan@greenplum.com>
Message-ID: <C0E9B584.8F43%jzhang@greenplum.com>
Thread-Topic: [HACKERS] On-disk bitmap index patch
Thread-Index: Acau6bjw97HAjBrcEdu9vAARJITXBg==
In-Reply-To: <Pine.LNX.4.58.0607240952250.19854@linuxworld.com.au>
MIME-Version: 1.0
Content-Type: text/plain;
 charset=us-ascii
Content-Transfer-Encoding: 7bit


Thanks Tom and Gavin for your comments!

Yes, this patch is generated against 8.2 in a short time. As long as the
code is working, I post the patch to get some comments and help.

>> 
>> * The xlog routines need help; they seem to not be updated for recent
>> changes in the API for xlog recovery code.
> 
> Yep. The patch was actually against 8.1 and was hastily brought up to 8.2.
> I think Jie's intention was to simply let everyone know that this was
> going on.

Thanks for pointing this out. I didn't notice that these are changed in 8.2.

> 
>> 
>> * The hacks on vacuum.c (where it tests the AM name) are utterly
>> unacceptable.  If you need the main code to do something special for a
>> particular index AM, define a bool flag column for it in pg_am.
> 
> Yes.

Sounds good.

> 
>> 
>> * The interface to the existing executor bitmap scan code is mighty
>> messy --- seems like there's a lot of almost duplicate code, a lot
>> of rather invasive hacking, etc.  This needs to be rethought and
>> refactored.
> 
> I agree.

I will think about this more.

> 
>> 
>> * Why in the world is it introducing duplicate copies of a lot
>> of btree comparison functions?  Use the ones that are there.
> 
> Yes, I raised this with Jie and she has fixed it. One thought is, we may
> want to rename those comparison functions prefixed with 'bm' to make their
> naming less confusing. They'll be used by btree, gin and bitmap index
> methods. Anyway, a seperate patch.

Yeah, the main problem I hesitated to use btree's comparison functions
because of those function names starting with 'bt'. Since Gavin told me that
Gin is using those functions as well, I had changed them. Renaming them
would be good.

> 
>> 
>> * The patch itself is a mess: it introduces .orig and .rej files,
>> changes around $PostgreSQL$ lines, etc.
>> 
> 
> Right, not to mention patches to configure and a lot of style which needs
> to be knocked into shape.
> 

The way I generate a patch is kind of clumsy. I need to find a better way to
do that.

I will start fixing these.

Thanks,
Jie