On 2014-03-17 19:58:18 -0400, Tom Lane wrote: > Alvaro Herrera <alvhe...@2ndquadrant.com> writes: > > Andres Freund wrote: > >> I think the best way to really cleanup a table is to use something like: > >> ALTER TABLE rew ALTER COLUMN data TYPE text USING (data); > >> where text is the previous type of the column. That should trigger a > >> full table rewrite, without any finesse about tracking ctid chains. > > > Isn't this what VACUUM FULL does? > > AFAIR, both VACUUM FULL and CLUSTER will attempt to preserve update > chains, and thus will probably get confused by this bug (though I've > not looked into exactly what will happen). I'm not real sure that ALTER > TABLE is any better --- doesn't all that stuff go through rewriteheap.c > now?
Nope, it's using ATRewriteTable(), which just does a loop around heap_getnext() and does a plain heap_insert(). Normally that's rather annoying because it completely destroys visibility information, but in this case... Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
