It appears I am running into this issue posted here
http://archives.postgresql.org/pgsql-general/2005-07/msg00693.php
The truncate gets a lock and waits for other transactions to finish.
Since the other transactions issue selects on the parent table(and thus
requiring a share lock on the child, due to the nature of partitioning),
the transactions get blocked.
This is bizarre. Why would truncate post a lock and thus block other
transactions when it should wait for the other transactions to finish
before acquiring a lock
-----Original Message-----
From: pgsql-admin-owner@postgresql.org
[mailto:pgsql-admin-owner@postgresql.org] On Behalf Of Tom Lane
Sent: Monday, June 19, 2006 6:24 PM
To: Sriram Dandapani
Cc: pgsql-admin@postgresql.org
Subject: Re: [ADMIN] truncate partitioned table locking
"Sriram Dandapani" <sdandapani@counterpane.com> writes:
> How can I issue a truncate /drop table on the child without running
into
> locking issues. Doesn't constraint exclusion prevent access of a child
> table based on the check constraint criteria
No, because the planner has to access the child table in order to
examine its constraints. (Since TRUNCATE is a metadata update, the
fact that the constraints are metadata not content doesn't help.)
TRUNCATE in itself is fast enough that you shouldn't really have any
problems here. If you are having locking issues then I suspect you need
to look for transactions that are sitting on ordinary reader or writer
locks of the table, instead of doing their jobs and committing.
regards, tom lane
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