Re: Correct docs re: rewriting indexes when table rewrite is skipped

Matthias van de Meent <boekewurm+postgres@gmail.com>

From: Matthias van de Meent <boekewurm+postgres@gmail.com>
To: James Coleman <jtc331@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-03-29T15:29:32Z
Lists: pgsql-hackers
On Tue, 29 Mar 2022 at 16:04, James Coleman <jtc331@gmail.com> wrote:
>
> Back in 367bc42 (for 9.2!) we "avoid[ed] index rebuild[ing] for
> no-rewrite ALTER TABLE
> .. ALTER TYPE." However the docs still claim that "a table rewrite is
> not needed; but any indexes on the affected columns must still be
> rebuilt."

Although indexes might indeed not need a rebuild, in many cases they
still do (e.g. when the type changes between text and a domain of text
with a different collation).

I think that the current state of the docs is better in that regard;
as it explicitly warns for index rebuilds, even when the letter of the
docs is incorrect: there are indeed cases we don't need to rebuild the
indexes; but that would require more elaboration.

Kind regards,

Matthias van de Meent



Commits

  1. docs: Changing column type doesn't always require an index rebuild.