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From: Dominique Devienne <ddevienne@gmail.com>
Date: Fri, 12 Sep 2025 15:24:29 +0200
Message-ID: <CAFCRh--M1y2YpJJMb6undzvyvhd4geKtRWFkDyr1shHvvoOkpQ@mail.gmail.com>
Subject: Re: Latest patches break one of our unit-test, related to RLS
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: pgsql-general@postgresql.org
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On Fri, Sep 12, 2025 at 3:11=E2=80=AFPM Dominique Devienne <ddevienne@gmail=
.com> wrote:
> On Fri, Sep 12, 2025 at 2:45=E2=80=AFPM Laurenz Albe <laurenz.albe@cybert=
ec.at> wrote:
> > You don't show us that data that match the pattern in 17.5, but
> > not in 17.6.  Unless you show us a counterexample, I'd say that
> > the behavior in 17.6 is correct.

I've reread https://www.postgresql.org/docs/current/functions-matching.html=
#FUNCTIONS-SIMILARTO-REGEXP
and especially:

> According to the SQL standard, omitting ESCAPE means there is no escape c=
haracter (rather than defaulting to a backslash), and a zero-length ESCAPE =
value is disallowed. PostgreSQL's behavior in this regard is therefore slig=
htly nonstandard.

and also

> Another nonstandard extension is that following the escape character with=
 a letter or digit provides access to the escape sequences defined for POSI=
X regular expressions; see Table 9.20, Table 9.21, and Table 9.22 below.

Table 9.21. Regular Expression Class-Shorthand Escapes
\d matches any digit, like [[:digit:]]
\w matches any word character, like [[:word:]]

So I don't see how my `... where v similar to 'foo[\d\w]_%'` is incorrect.

So again, is this a bug / regression or not? Thanks, --DD