Re: graph representation of data structures in optimizer - Mailing list pgsql-hackers

From Gregory Stark
Subject Re: graph representation of data structures in optimizer
Date
Msg-id 87zlgjzpj6.fsf@oxford.xeocode.com
Whole thread Raw
In response to graph representation of data structures in optimizer  (Adriano Lange <adriano@c3sl.ufpr.br>)
Responses Re: graph representation of data structures in optimizer  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Adriano Lange <adriano@c3sl.ufpr.br> writes:

> Hi,
>
> I'm interested in data representation and debug of optimizer routines. Thus,
> I've changed the debug functions of allpaths.c to make a graphviz-like output
> of RelOptInfo structure.
>
> Any idea about this?
> Is there some project or improvement like this?

Several people have asked about ways to see what possible plans were
considered and why the were rejected, it was one of the repeat offenders in
the recent Postgres Pet Peeves thread so this is a very interesting area to
explore.

However I have to say this graph you've generated is amazingly hard to
decipher :) It took me a while to even figure out what information it was
presenting.

Worse, it's not useful unless you add a lot more information to it such as
what relations are actually being scanned or joined at each path which is
going to make it a hell of a lot harder to read.

I'm not sure how to do any better but I would be fascinated to see any new
images you generate :)

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com Ask me about EnterpriseDB's PostGIS support!


pgsql-hackers by date:

Previous
From: Simon Riggs
Date:
Subject: Re: Hot standby, recovery infra
Next
From: Mohsen Alimomeni
Date:
Subject: Multi calendar system for pgsql