From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Hills <mark@xwax.org>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Domain check taking place unnecessarily?
Date: Thu, 09 Feb 2023 10:10:01 -0500
Message-ID: <3893890.1675955401@sss.pgh.pa.us> (raw)
In-Reply-To: <2302091035450.14632@stax.localdomain>
References: <2302081605290.5352@stax.localdomain>
<4b1a0c9e36280b1d4abeb4fb6336832409df6ae0.camel@cybertec.at>
<2302091035450.14632@stax.localdomain>
Mark Hills <mark@xwax.org> writes:
> On Wed, 8 Feb 2023, Laurenz Albe wrote:
>> It takes 30 seconds to schan the table and determine that all existing
>> rows satisky the constraint.
> But there's no existing data (note this is adding column, not constraint)
> Existing rows are guaranteed to satisfy the domain check, because the
> domain check is guaranteed to be immutable (per [1] in my original mail)
immutable != "will accept null".
There could be some more optimizations here, perhaps, but there aren't.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, mark@xwax.org, laurenz.albe@cybertec.at, pgsql-performance@lists.postgresql.org
Subject: Re: Domain check taking place unnecessarily?
In-Reply-To: <3893890.1675955401@sss.pgh.pa.us>
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