Message-ID: <5CF2754F.7000702@anastigmatix.net>
Date: Sat, 01 Jun 2019 08:53:35 -0400
From: Chapman Flack <chap@anastigmatix.net>
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To: Alvaro Herrera <alvherre@2ndquadrant.com>
CC: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: PostgreSQL vs SQL/XML Standards
References: <20190531200438.GA26307@alvherre.pgsql>
In-Reply-To: <20190531200438.GA26307@alvherre.pgsql>
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On 05/31/19 16:04, Alvaro Herrera wrote:

> https://www.iso.org/standard/41528.html "XQuery Regular Expression
> Support in SQL"

Although I hadn't seen that particular document, I did see those in the
SQL spec and mention them in the wiki page [1].

I should point out that's also a conformance note in the new SQL/JSON
support [2], as the standard specifies XQuery regular expressions for
jsonpath's like_regex predicate, where we're applying POSIX ones
instead.

Doesn't change my thinking much ... I think we should support the
stuff. :) ... using a non-in-house-developed XQuery library to do it,
or better yet, a choice of non-in-house-developed XQuery libraries.

I still think the second idea I suggested on the wiki seems like the
most promising road map [3], though it'll involve a few preparatory
stops along the way.

-Chap


[1]
https://wiki.postgresql.org/wiki/PostgreSQL_vs_SQL/XML_Standards#XML_Query_regular_expressions

[2]
https://github.com/obartunov/sqljsondoc/blob/master/README.jsonpath.md#sqljson-conformance

[3]
https://wiki.postgresql.org/wiki/PostgreSQL_vs_SQL/XML_Standards#Proposal_2:_desugaring_to_calls_on_normal_extension_functions