From: Dawid Kuroczko <qnex42@gmail.com>
To: weigelt@metux.de
Cc: pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: Finding broken regex'es
Date: Wed, 3 Oct 2007 15:36:41 +0200
Message-ID: <758d5e7f0710030636m63bec244paa6cbaf04e66b3d2@mail.gmail.com> (raw)
In-Reply-To: <20071002202313.GB18506@nibiru.local>
References: <20071002202313.GB18506@nibiru.local>
On 10/2/07, Enrico Weigelt <weigelt@metux.de> wrote:
>
> Hi folks,
>
>
> I'm looking for some way to find broken regex'es in some column
> to kick them off. For now I'm regularily fetching all regexes
> from an PHP script, try an preg_match() and so find the broken
> ones to later remove them.
>
> Is there any way to do this directly within the db ?
Of course. Exceptions is what You need!
CREATE FUNCTION regex_is_broken(r text) RETURNS boolean AS $$
BEGIN
PERFORM '' ~ r;
RETURN 'f';
EXCEPTION
WHEN INVALID_REGULAR_EXPRESSION THEN
RETURN 't';
END;
$$ LANGUAGE PLpgSQL STRICT IMMUTABLE;
...and then you could do something like:
DELETE FROM table WHERE regex_is_broken(rx_col);
You don't need PLpgSQL to prevent such invalid regexes in the
first place. You could use CHECK constraint for it:
CREATE TABLE rx_check (
rx text CHECK ('' ~ rx IN ('t','f'))
);
postgres=> INSERT INTO rx_check (rx) VALUES ('.*');
INSERT 0 1
Time: 13.660 ms
postgres=> INSERT INTO rx_check (rx) VALUES ('234234');
INSERT 0 1
Time: 2.282 ms
postgres=> INSERT INTO rx_check (rx) VALUES ('par).*');
ERROR: invalid regular expression: parentheses () not balanced
Regards,
Dawid
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To: pgsql-sql@postgresql.org
Cc: qnex42@gmail.com, weigelt@metux.de
Subject: Re: Finding broken regex'es
In-Reply-To: <758d5e7f0710030636m63bec244paa6cbaf04e66b3d2@mail.gmail.com>
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