Alter doesn't lock the table - but it will slow down the server. If you're starting with 650GB table I expect you to come out with, more or less 200GB after the compression.
Obviously yes, you need the space for the new table as the process of alter is creating the new table and then dropping the old one. --- Andrea Brancatelli Schema31 S.p.a. Responsabile IT ROMA - BO - FI - PA ITALY Tel: +39. 06.98.358.472 Cell: +39 331.2488468 Fax: +39. 055.71.880.466 Società del Gruppo SC31 ITALIA Il 2016-03-03 22:08 Simon Buchanan ha scritto: > On 3 March 2016 at 11:36:59 PM, Andrea Brancatelli (abrancate...@schema31.it) > wrote: > >> Yes you can proceed easily with those two settings and have a first bigger >> improvement. >> >> If you're switching away from dbmail I wouldn't go trough the hassle of >> upgrading, since the upgrade need to reparse all the message to use the >> de-deduplication features. >> >> Note: the ALTER TABLE will perform the OPTIMIZE TABLE, so you don't need to >> run the two commands, just go for the ALTER TABLE. > > Thanks for the reply - my thoughts with the upgrade. The issue with OPTIMISE > TABLE is that it needs the same amount of space to do the optimise, plus the > tables are write locked whist this happens (is this correct?). Thats going to > take a while on a 650GB table :) with live data on it. > > Does Alter table write lock as well? > > PS: also - what do i alter... > > Simon > > _______________________________________________ > DBmail mailing list > DBmail@dbmail.org > http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail
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