Re: BUG #5469: regexp_matches() has poor behaviour and more poor documentation

From: Jasen Betts <jasen(at)xnet(dot)co(dot)nz>
To: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #5469: regexp_matches() has poor behaviour and more poor documentation
Date: 2010-05-27 07:56:16
Message-ID: htl8j0$aau$2@reversiblemaps.ath.cx
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On 2010-05-26, Daniele Varrazzo <daniele(dot)varrazzo(at)gmail(dot)com> wrote:

> [regexp_matches:] Return all groups of captured substrings resulting
> from matching a POSIX regular expression against the string. Warning:
> in case of no match, tested record is dropped. See Section 9.7.3 for
> more information.

possibly like this instead.

[regexp_matches:] Return all groups of captured substrings resulting
from matching a POSIX regular expression against the string. Note:
one row is returned for each match, no matches results in no rows,
several matches results in several rows.

> In section 9.7.3, after "If there is no match to the pattern, the
> function returns no rows." I would add "This means that if the
> function is used in a SELECT, records where the string don't match the
> pattern are discarded from the dataset. If such records are required,
> use regexp_match() instead".

or use an outer join to a subquery if you want to see all the results.

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