On Wed, Sep 18, 2013 at 2:06 AM, Andres Freund <and...@2ndquadrant.com> wrote: > On 2013-09-17 23:12:24 -0700, Sergey Konoplev wrote: >> How safe is it to use the technique described by the link below with >> system catalog tables to remove bloat? >> (in a couple of words it is about moving tuples to the beginning of >> the table with a special way of updating) >> http://www.depesz.com/2010/10/17/reduce-bloat-of-table-without-longexclusive-locks/ > > At least for pg_index it's not safe, we use the xmin of rows when > indcheckxmin = true. > I am not aware of other cases, but I'd be hesitant to do so.
Thank you, Andres, I did not know this. Just wondering, why it was made of type bool and not xid? > You have bloat because of lots of temporary tables IIRC? Actually I am developing a bloat removing tool based on the updating technique: https://code.google.com/p/pgtoolkit/source/browse/trunk/README Now the --system-catalog feature marked as experimental. About pg_index - I think the solution is to exclude it from processing strictly. Anyone has other ideas of what system tables it might be affected except pg_index? -- Kind regards, Sergey Konoplev PostgreSQL Consultant and DBA http://www.linkedin.com/in/grayhemp +1 (415) 867-9984, +7 (901) 903-0499, +7 (988) 888-1979 gray...@gmail.com -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers