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help / color / mirror / Atom feedFrom: Laurenz Albe <laurenz.albe@cybertec.at>
To: Steve Lau <stevelauc@outlook.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: david.g.johnston@gmail.com <david.g.johnston@gmail.com>
Cc: pgsql-docs@postgresql.org <pgsql-docs@postgresql.org>
Subject: Re: Index of expression over table row or column
Date: Wed, 16 Oct 2024 06:17:01 +0200
Message-ID: <fb83431b59299474a44353f70f552c7fd34e73f7.camel@cybertec.at> (raw)
In-Reply-To: <FA21AE90-C2BC-40AD-8906-C646CA2EAE98@outlook.com>
References: <964FED20-AC2E-47C5-86FB-95C356A68B81@outlook.com>
<4169601.1729048988@sss.pgh.pa.us>
<FA21AE90-C2BC-40AD-8906-C646CA2EAE98@outlook.com>
On Wed, 2024-10-16 at 04:00 +0000, Steve Lau wrote:
> Regarding Tom’s reply, IMHO, “LOWER(last_name || ' ' || first_name)” is still an
> expression over table columns? Would you like to elaborate on it a bit?
Well, a table row consists of columns. So something that depends on or uses several
columns can be said to be "on the table row". I'd say that the documentation is
correct, but if it gives you trouble, perhaps it should be improved.
And what would you say about this (silly) example:
CREATE TABLE x (a integer, b integer);
CREATE INDEX ON x(hash_record(x));
Yours,
Laurenz Albe
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Cc: laurenz.albe@cybertec.at, stevelauc@outlook.com, tgl@sss.pgh.pa.us, david.g.johnston@gmail.com
Subject: Re: Index of expression over table row or column
In-Reply-To: <fb83431b59299474a44353f70f552c7fd34e73f7.camel@cybertec.at>
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