From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: Michel Helms <michel@togetherdb.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: pg_table_size errors "invalid name syntax" for table names
 containing spaces
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Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Thu, 10 Jun 2021 05:25:04 -0700"
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Date: Thu, 10 Jun 2021 09:43:37 -0400
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Thursday, June 10, 2021, Michel Helms <michel@togetherdb.com> wrote:
>> CREATE TABLE "wei rd" (id SERIAL);
>> SELECT pg_table_size('wei rd');

> You still have to double-quote the name even if its being passed around in
> a string literal.

Yeah.  The reason for this is that you're also allowed to write qualified
table names:

SELECT pg_table_size('myschema.mytable');

That would seem to introduce an ambiguity: is the dot a schema separator,
or just an ordinary character (in a table name that was presumably written
with double quotes originally)?  We resolve this by saying that the
parsing rules for regclass_in are the same as they are in SQL text,
so you have to double-quote anything that is not a plain identifier
or needs to be protected against case-folding.

Hence, you should write

SELECT pg_table_size('"wei rd"');

			regards, tom lane