Subject: Re: [PROPOSAL] Max recursion depth in WITH Queries (Common
 Table Expressions)
To: pgsql-hackers@postgresql.org
References: <56307A3F.4050802@postgrespro.ru> <18351.1446039187@sss.pgh.pa.us>
From: Valery Popov <v.popov@postgrespro.ru>
Message-ID: <5630E28E.6070409@postgrespro.ru>
Date: Wed, 28 Oct 2015 17:58:22 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <18351.1446039187@sss.pgh.pa.us>
Content-Type: text/plain; charset=windows-1251; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org


28.10.2015 16:33, Tom Lane ןטרוע:
> Valery Popov <v.popov@postgrespro.ru> writes:
>> Recursive queries are typically used to deal with hierarchical or
>> tree-structured data.
>> In some conditions when data contain  relationships with cycles recursive query will loop
>> unlimited and significantly slows the client's session.
> The standard way of dealing with that is to include logic in the query to
> limit the recursion depth, for example
>
> WITH RECURSIVE t(n) AS (
>      SELECT 1
>    UNION ALL
>      SELECT n+1 FROM t WHERE n < 10
> )
> SELECT n FROM t;
>
Yes, I agree with this thesis.  But I think in some cases would be 
better to receive error message and stop execution than results will 
incomplete.

-- 
Regards,
Valery Popov
Postgres Professional http://www.postgrespro.com
The Russian Postgres Company


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers