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From: Tom Lane <[email protected]>
To: Marcelo Lauxen <[email protected]>
Cc: [email protected]
Subject: Re: pg_get_indexdef() output not idempotent for partial indexes with ALL(ARRAY[…])::text[]
Date: Wed, 13 May 2026 09:51:39 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CANKisB3AG6JK1tCMp4myj75tF3t93pEK_ojECdJ=Fnin-E+J_A@mail.gmail.com>
References: <CANKisB3AG6JK1tCMp4myj75tF3t93pEK_ojECdJ=Fnin-E+J_A@mail.gmail.com>

Marcelo Lauxen <[email protected]> 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

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