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: Richard Guo <guofenglinux@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-03-21T17:21:43Z
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:
> However, I'm a bit concerned about the overall premise of the patch
> set. It feels like it is moving something that really ought to happen
> at optimization time back to parse time. I have a feeling that's going
> to break something, although I am not sure right now exactly what.

Ugh, no, that is *completely* unworkable.  Suppose that the user
does CREATE VIEW, and the parse tree recorded for that claims that
column X is not-nullable.  Then the user drops the not-null
constraint, and then asks to execute the view.  We'll optimize on
the basis of stale information.

The way to make this work is what I said before: move the planner's
collection of relation information to somewhere a bit earlier in
the planner.  But not to outside the planner.

			regards, tom lane