Horton

Re: using index or check in ALTER TABLE SET NOT NULL

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: David Rowley <david.rowley@2ndquadrant.com>, Sergei Kornilov <sk@zsrv.org>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, David Steele <david@pgmasters.net>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Stephen Frost <sfrost@snowman.net>, Ildar Musin <i.musin@postgrespro.ru>
Date: 2019-08-02T20:02:20Z
Lists: pgsql-hackers 
Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
> I think there's a consensus to change INFO to DEBUG1 in pg12, and then
> maybe imlpement something like VERBOSE mode in the future. Objections?

ISTM the consensus is "we'd rather reduce the verbosity, but we don't
want to give up test coverage".  So what's blocking this is lack of
a patch to show that there's another way to verify what code path
was taken.

> As for the reduction of test coverage, can't we deduce whether a
> constraint was used from data in pg_stats or something like that?

Not sure how exactly ... and we've already learned that pg_stats
isn't too reliable.

			regards, tom lane

Commits

  1. Avoid using INFO elevel for what are fundamentally debug messages.

  2. Revert setting client_min_messages to 'debug1' in new tests.

  3. Allow ALTER TABLE .. SET NOT NULL to skip provably unnecessary scans.

  4. Improve predtest.c's internal docs, and enhance its functionality a bit.