Date: Tue, 22 Jan 2019 19:55:15 -0500
From: Bruce Momjian <bruce@momjian.us>
To: f2381430@mvrht.com, pgsql-docs@lists.postgresql.org
Subject: Re: Undocumented behaviour of \s in SIMILAR TO expression
Message-ID: <20190123005515.GC1493@momjian.us>
References: <154470529073.5057.10757027183683688588@wrigleys.postgresql.org>
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On Thu, Dec 13, 2018 at 12:48:10PM +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
> 
> Page: https://www.postgresql.org/docs/11/functions-matching.html
> Description:
> 
> SELECT ' ' SIMILAR TO '[\s]';
> returns true
> 
> SELECT ' ' SIMILAR TO '[\q]';
> generates an error: [2201B]: ERROR: invalid regular expression: invalid
> escape \ sequence
> 
> \s is not mentioned in the SIMILAR TO section
> (https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-SIMILARTO-REGEXP).
> If it’s officially supported (which would be useful for my current task), it
> should be documented. Otherwise the server should generate an error like for
> other invalid escapes.

Well in:

	https://www.postgresql.org/docs/11/functions-matching.html

I see \s documented, but not \q:

	Table 9.19. Regular Expression Class-shorthand Escapes
	Escape 	Description
	\d 	[[:digit:]]
	\s 	[[:space:]]
	\w 	[[:alnum:]_] (note underscore is included)
	\D 	[^[:digit:]]
	\S 	[^[:space:]]
	\W 	[^[:alnum:]_] (note underscore is included)

Frankly, I can't even guess what you expect \q to do.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
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