On Tue, Mar 9, 2021 at 2:45 AM Robert Haas <robertmh...@gmail.com> wrote: > > On Mon, Mar 8, 2021 at 3:59 PM Justin Pryzby <pry...@telsasoft.com> wrote: > > > It would be nice to have a way to force > > > anything compressed with the old method to be re-compressed with the > > > new method, but not having that doesn't preclude allowing the > > > parameter to be changed. > > > > Doesn't vacuum full/cluster/dump+restore do that ? > > Well, dump and restore will do it, certainly, but I don't think VACUUM > FULL or CLUSTER will. I haven't tested it, though, so maybe I'm wrong.
Yeah, vacuum full or cluster will not re-compress the data. How about providing syntax ALTER TABLE <tab-name> ALTER COLUMN <col_name> SET COMPRESSION <com_name> REWRITE? So if we have given a rewrite then we will always rewrite the table and in an attempt to rewrite we will re-compress the data. If REWRITE is given and the compression method is the same as the existing then also we can not skip the rewrite because we don't know the history, the user might alter the compression method multiple times without rewrite. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
