Re: pg_get_indexdef() output not idempotent for partial indexes with ALL(ARRAY[…])::text[]

Marcelo Lauxen <marcelolauxen16@gmail.com>

From: Marcelo Lauxen <marcelolauxen16@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-bugs@lists.postgresql.org
Date: 2026-05-13T14:25:47Z
Lists: pgsql-bugs
Gotcha, it wasn't clear to me that this was never guaranteed. I will change
the type of this column to text to resolve this.

Appreciate the quick response!

Regards,
Marcelo

On Wed, May 13, 2026 at 10:51 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Marcelo Lauxen <marcelolauxen16@gmail.com> writes:
> > *PostgreSQL version*: 18.3 (Homebrew) on aarch64-apple-darwin24.6.0
> > *pg_get_indexdef()* produces SQL that, when executed, yields a different
> > pg_get_indexdef() output. This means a pg_dump → pg_restore cycle
> silently
> > changes the deparsed form of partial index WHERE clauses that use NOT IN
> > (...) on a varchar column, causing cosmetic drift in tools that compare
> > index definitions (e.g. ORM schema dumps, annotation generators).
>
> You are assuming a property that we've never guaranteed and don't plan
> to start guaranteeing, ie that the output of expression decompilation
> matches the input even in semantically-insignificant details.
>
> My own advice about how to fix this particular example is not to use
> varchar --- especially not unconstrained varchar, which doesn't even
> have the thin excuse of being spec-compliant.  Postgres' native string
> type is text.
>
>                         regards, tom lane
>