Horton

Re: Reduce "Var IS [NOT] NULL" quals during constant folding

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Eisentraut <peter@eisentraut.org>, Richard Guo <guofenglinux@gmail.com>, David Rowley <dgrowleyml@gmail.com>, Tender Wang <tndrwang@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-05-22T14:51:30Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix misuse of Relids for storing attribute numbers

  2. Reduce "Var IS [NOT] NULL" quals during constant folding

  3. Centralize collection of catalog info needed early in the planner

  4. Expand virtual generated columns before sublink pull-up

  5. Expand virtual generated columns in the planner

Robert Haas <robertmhaas@gmail.com> writes:
> Before we commit to something along these lines, I think we need to
> understand whether Tom intends to press Peter for some bigger change
> around expand_virtual_generated_columns.
> If Tom doesn't respond right away, I suggest that we need to add an
> open item for http://postgr.es/m/602561.1744314879@sss.pgh.pa.us

I think that we do need to do something about that, but it may be
in the too-late-for-v18 category by now.  Not sure.  I definitely
don't love the idea of table_open'ing every table in every query
an extra time just to find out (about 99.44% of the time) that it
does not have any virtual generated columns.

I wonder if a better answer would be to make the rewriter responsible
for this.  If you hold your head at the correct angle, a table with
virtual generated columns looks a good deal like a view, and we don't
ask the planner to handle those.

BTW, in my mind the current thread is certainly v19 material,
so I have not looked at Richard's patch yet.

			regards, tom lane