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From: Greg Sabino Mullane <[email protected]>
To: Nico Heller <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: Guarantee order of batched pg_advisory_xact_lock
Date: Thu, 12 Feb 2026 09:47:39 -0500
Message-ID: <CAKAnmmKfV4K6CfMuQkfQxccP0JRC5orV1tmaq8pB_+EdCZS1yw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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On Thu, Feb 12, 2026 at 6:18 AM Nico Heller <[email protected]> wrote:

> I just checked for hash collisions with the following query today:
>
> SELECT COUNT(*), hashtextextended(key, 0) FROM
> (
>   SELECT key FROM table1
>   UNION
>

FWIW, you need UNION ALL, not UNION, if you are trying to detect duplicate
values (hashed or not) across tables.

Cheers,
Greg

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