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CLUSTER, using SHARE UPDATE EXCLUSIVE lock?

From: Jonathan Scher <js(at)oxado(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: CLUSTER, using SHARE UPDATE EXCLUSIVE lock?
Date: 2007-03-01 13:55:35
Message-ID: 45E6DB57.6000107@oxado.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Hello,

CLUSTER uses an ACCESS EXCLUSIVE lock. Why does it forbid concurrent reads?
Florian G. Pflug, on a post ( 
http://archives.postgresql.org/pgsql-hackers/2007-02/msg00081.php ) 
suggested that there were no way to let the old entry until the command 
commit.
I would like Cluster to create a new table, copying old values to this 
one, then delete the old one. This would allow Cluster to work with a 
share update exlusive lock, in order to allow reading the table while 
cluster is working.

How does Cluster actually works? Why making a Cluster command less 
restrictive isn't even in the TO-list?

Best regards,
Jonathan Scher

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