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Re: EXPLAIN Node Docs?

From: "David E(dot) Wheeler" <david(at)kineticode(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "pgsql-hackers(at)postgresql(dot)org Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: EXPLAIN Node Docs?
Date: 2011-04-29 23:28:09
Message-ID: A4360496-002D-4D3E-B62C-29160EC3F2AD@kineticode.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Apr 29, 2011, at 2:07 PM, Tom Lane wrote:

> In particular, src/include/nodes/plannodes.h is pretty well commented.

Ah, that's a useful file to scan, thanks.

> If it's not immediately obvious how that maps to what's shown by
> EXPLAIN, look into commands/explain.c.

Yeah, that's the file I have been reading.

> (There are things that aren't
> mentioned by EXPLAIN even in verbose mode, such as which columns Group
> is going to group by; usually that's because it's redundant with info
> available elsewhere, such as the sort columns of a lower sort node.)

Right, I figured that one out. Same does not appear to be true of Filter elements, though.

> Keep in mind also that we reserve the right to whack these things around
> in arbitrary ways from one release to the next.

Yeah, though I assume you mean major releases, not maintenance releases. Still, it'd be nice to have a documentation reference.

Best,

David


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