Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtps  (TLS1.3) tls
 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.94.2)
	(envelope-from <pgsql-bugs-owner+archive@lists.postgresql.org>)
	id 1vGepx-003R0H-Kp
	for pgsql-bugs@arkaria.postgresql.org; Wed, 05 Nov 2025 14:50:12 +0000
Received: from localhost ([127.0.0.1] helo=malur.postgresql.org)
	by malur.postgresql.org with esmtp (Exim 4.94.2)
	(envelope-from <pgsql-bugs-owner+archive@lists.postgresql.org>)
	id 1vGepw-0038CG-JK
	for pgsql-bugs@arkaria.postgresql.org; Wed, 05 Nov 2025 14:50:11 +0000
Received: from makus.postgresql.org ([2001:4800:3e1:1::229])
	by malur.postgresql.org with esmtps  (TLS1.3) tls
 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.94.2)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1vGepw-0038C8-AH
	for pgsql-bugs@lists.postgresql.org; Wed, 05 Nov 2025 14:50:11 +0000
Received: from sss.pgh.pa.us ([68.162.161.243])
	by makus.postgresql.org with esmtps  (TLS1.3) tls
 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.96)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1vGept-005bBb-1x
	for pgsql-bugs@lists.postgresql.org;
	Wed, 05 Nov 2025 14:50:10 +0000
Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1])
	by sss.pgh.pa.us (8.15.2/8.15.2) with ESMTP id 5A5Enuc2812835;
	Wed, 5 Nov 2025 09:49:56 -0500
From: Tom Lane <tgl@sss.pgh.pa.us>
To: zoulx1982@163.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19104: Does regexp_substr function support non-greedy
 matching?
In-reply-to: <19104-c9e08a2693264d98@postgresql.org>
References: <19104-c9e08a2693264d98@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Wed, 05 Nov 2025 12:41:30 +0000"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <812833.1762354196.1@sss.pgh.pa.us>
Content-Transfer-Encoding: quoted-printable
Date: Wed, 05 Nov 2025 09:49:56 -0500
Message-ID: <812834.1762354196@sss.pgh.pa.us>
List-Id: <pgsql-bugs.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-bugs@lists.postgresql.org>
List-Owner: <mailto:pgsql-bugs-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-bugs>
Archived-At: 
 <https://www.postgresql.org/message-id/812834.1762354196%40sss.pgh.pa.us>
Precedence: bulk

PG Bug reporting form <noreply@postgresql.org> writes:
> When i use regexp_substr to process some text file, i found regexp_subst=
r
> does not support non-greedy match.

Sure it does.  But the details of the behavior are different from
Perl's engine in cases where you have both greedy and non-greedy
quantifiers (as your example does).  Read the greediness rules here:

https://www.postgresql.org/docs/current/functions-matching.html#POSIX-MATC=
HING-RULES

			regards, tom lane