From: Julien Cigar <jcigar@ulb.ac.be>
To: pgsql-sql@postgresql.org
Subject: WITH RECURSIVE question
Date: Tue, 23 Aug 2011 12:03:43 +0200
Message-ID: <4E537AFF.8050006@ulb.ac.be> (raw)
Hello,
I have a classic parent -> child relation (id, container_id) and I would
like to find the full hierarchy for a child, something like
A
/ \
B C
|
D
given D I want {A,B,C}
WITH RECURSIVE hierarchy(level, container_id, titles, containers) AS
(SELECT 1 AS level, container_id, ARRAY[title::text] AS titles,
ARRAY[container_id] AS containers
FROM content
WHERE id=984
UNION ALL
SELECT hierarchy.level + 1, c.container_id,
array_prepend(c.title::text, titles),
array_prepend(c.container_id, containers)
FROM content c
JOIN hierarchy ON hierarchy.container_id = c.id
) SELECT titles, containers
FROM hierarchy
ORDER BY level DESC LIMIT 1;
which give me something like:
titles | containers
----------------------+--------------
{Home,Templates,IAS} | {NULL,1,983}
(1 row)
This is exactly what I want, but I wondered if there are better ways to
do it? Is it scalable?
(The final idea is to put that in a trigger, so that it will be executed
only when a new row is added, or when the row is moved from a container
to another one ..)
Thanks,
Julien
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Subject: Re: WITH RECURSIVE question
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