Message-ID: <f3d6bcc63fdbd80d98ccbef975df5f0a55f58cd9.camel@j-davis.com>
Subject: Re: should check collations when creating partitioned index
From: Jeff Davis <pgsql@j-davis.com>
To: Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers
	 <pgsql-hackers@postgresql.org>
Date: Fri, 17 Nov 2023 12:02:33 -0800
In-Reply-To: <3327cb54-f7f1-413b-8fdb-7a9dceebb938@eisentraut.org>
References: <3327cb54-f7f1-413b-8fdb-7a9dceebb938@eisentraut.org>
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On Mon, 2023-11-13 at 10:24 +0100, Peter Eisentraut wrote:
> create table t1 (a int, b text) partition by hash (b);
> create table t1a partition of t1 for values with (modulus 2,
> remainder 0);
> create table t1b partition of t1 for values with (modulus 2,
> remainder 1);
> create unique index i1 on t1 (b collate case_insensitive);
> insert into t1 values (1, 'a'), (2, 'A');=C2=A0 -- this succeeds
>=20
> The attached patch adds the required collation check.=C2=A0 In the
> example,=20
> it would not allow the index i1 to be created.

In the patch, you check for an exact collation match. Considering this
case only depends on equality, I think it would be correct if the
requirement was that (a) both collations are deterministic; or (b) the
collations match exactly.

This is related to the discussion here:

https://postgr.es/m/b7a9f32eee8d24518f791168bc6fb653d1f95f4d.camel@j-davis.=
com

Regards,
	Jeff Davis