Horton

Re: Changed SRF in targetlist handling

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Joe Conway <mail@joeconway.com>
Cc: Merlin Moncure <mmoncure@gmail.com>, David Fetter <david@fetter.org>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-05-23T20:17:55Z
Lists: pgsql-hackers 
Joe Conway <mail@joeconway.com> writes:
> I would be in favor of rewriting it to a LATERAL, but that would not be
> backwards compatible entirely either IIUC.

It could be made so, I think, but it may be more trouble than it's worth;
see my previous message.

> I'll also note that, unless I missed something, we also have to consider
> that the capability to pipeline results is still only available in the
> target list.

Yes, we would definitely want to improve nodeFunctionscan.c to perform
better for ValuePerCall SRFs.  But that has value independently of this.

			regards, tom lane

Commits

  1. Remove obsoleted code relating to targetlist SRF evaluation.

  2. Doc: improve documentation of new SRF-in-tlist behavior.

  3. Move targetlist SRF handling from expression evaluation to new executor node.

  4. Don't split up SRFs when choosing to postpone SELECT output expressions.