1) Yes
All rows are treated the same, there are no in place updates.
2) No
Truncate recreates the object as a new one, releasing the space held by the old one.
- Luke
Msg is shrt cuz m on ma treo
-----Original Message-----
From: Scott Feldstein [mailto:scott.feldstein@hyperic.com]
Sent: Thursday, July 26, 2007 06:44 PM Eastern Standard Time
To: pgsql-performance@postgresql.org
Subject: [PERFORM] update, truncate and vacuum
Hi,
I have a couple questions about how update, truncate and vacuum would
work together.
1) If I update a table foo (id int, value numeric (20, 6))
with
update foo set value = 100 where id = 1
Would a vacuum be necessary after this type of operation since the
updated value is a numeric? (as opposed to a sql type where its size
could potentially change i.e varchar)
2) After several updates/deletes to a table, if I truncate it, would
it be necessary to run vacuum in order to reclaim the space?
thanks,
Scott
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