You can change your configuration such that the tables that you're
looking to alter are in their own set.  That will still cause them to be
locked, but at least it won't cause the other ones to be locked.

Also, in certain situations you might be able to run the alter command
on each of the slaves and then on the master.  E.g. if you're adding a
new column that allows null values, then it might be possible to alter
the slaves even while rows are being inserted into the master.  You will
still be taking a lock on the table while altering it, but at least
you're not locking multiple tables at a time across multiple machines.
Not sure if this is recommended practice.

--S

-----Original Message-----
From: slony1-general-bounces at lists.slony.info
[mailto:slony1-general-bounces at lists.slony.info] On Behalf Of Cyril
SCETBON
Sent: Tuesday, July 01, 2008 3:01 AM
To: slony1-general at lists.slony.info
Subject: [Slony1-general] how to prevent EXECUTE SCRIPT from locking
alltables

Hi,

We got a cluster configuration with something like 500 tables. Sometimes

we have to add columns to tables. Today we're using execute script which

locks all tables and not only the tables that belong to the set 
specified in this command. We have a lot of DML statement and these 
locks are really disturbing our application.

Are there other possibilities of using EXECUTE SCRIPT ? Is there a bad 
and a good use of this command ?

Thanks
-- 
Cyril SCETBON
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