Horton

Re: Generated column is not updated (Postgres 13)

Vitaly Ustinov <vitaly@ustinov.ca>

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From: Vitaly Ustinov <vitaly@ustinov.ca>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, pgsql-bugs@lists.postgresql.org, "David G. Johnston" <david.g.johnston@gmail.com>
Date: 2021-05-20T19:07:34Z
Lists: pgsql-bugs 
In a BEFORE trigger (PL/pgSQL) I can access not yet computed generated
columns via the "NEW" whole-row var. I can read from it (NULL), and I
can write to it, but the assigned value will be ignored.

This behavior seems obvious and well thought through to me. It's not
something app developers should do, because it wouldn't make sense,
but at least it's not forbidden and the server process does not crash
with a seg fault.

Is it okay with you that the patch 0002 introduces some inconsistency with that?

Regards,
Vitaly

Commits

  1. Disallow whole-row variables in GENERATED expressions.

  2. Fix usage of "tableoid" in GENERATED expressions.