Re: Proposal: Add a UNIQUE NOT ENFORCED constraint

From: Jacob Jackson <jej(dot)jackson(dot)08(at)gmail(dot)com>
To: Joel Jacobson <joel(at)compiler(dot)org>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Proposal: Add a UNIQUE NOT ENFORCED constraint
Date: 2026-01-08 01:31:44
Message-ID: CAAiQw3zf2Mzvsi5cd1RA6=ojnq5nyoNyYfE_Gkq-g4LkB_wmTA@mail.gmail.com
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On Tue, Jan 6, 2026 at 1:44 AM Joel Jacobson <joel(at)compiler(dot)org> wrote:
> Can you please share some more details on your use-case?
> I'm curious to learn more about this "unique" column.
> Don't you ever need to do lookups/joins on it (e.g. WHERE col = ?)

The unique column (technically 2 columns that combined are unique)
functions as a pretty typical id. Yes, I do run joins on it, but the
performance advantage of an additional index is outweighed by the
ingest performance hit due to the cardinality of the outer relation
(hash joins are typically used) and the relatively small row size.

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