Message-ID: <fb83431b59299474a44353f70f552c7fd34e73f7.camel@cybertec.at>
Subject: Re: Index of expression over table row or column
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Steve Lau <stevelauc@outlook.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 "david.g.johnston@gmail.com"
	 <david.g.johnston@gmail.com>
Cc: "pgsql-docs@postgresql.org" <pgsql-docs@postgresql.org>
Date: Wed, 16 Oct 2024 06:17:01 +0200
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>
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On Wed, 2024-10-16 at 04:00 +0000, Steve Lau wrote:

> Regarding Tom=E2=80=99s reply, IMHO, =E2=80=9CLOWER(last_name || ' ' || f=
irst_name)=E2=80=9D 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 use=
s several
columns can be said to be "on the table row".  I'd say that the documentati=
on 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