On Wed, 2010-12-15 at 10:54 +0100, Csaba Nagy wrote: > On Tue, 2010-12-14 at 14:36 -0500, Robert Haas wrote: > > > Well, you have to do that for DROP TABLE as well, and I don't see any > > > way around doing it for REPLACE WITH. > > > > Sure, but in Simon's proposal you can load the data FIRST and then > > take a lock just long enough to do the swap. That's very different > > from needing to hold the lock during the whole data load. > > Except Simon's original proposal has this line in it: > > * "new_table" is TRUNCATEd. > > I guess Simon mixed up "new_table" and "old_table", and the one which > should get truncated is the replaced one and not the replacement, > otherwise it doesn't make sense to me.
What I meant was... REPLACE TABLE target WITH source; * target's old rows are discarded * target's new rows are all of the rows from "source". * source is then truncated, so ends up empty Perhaps a more useful definition would be EXCHANGE TABLE target WITH source; which just swaps the heap and indexes of each table. You can then use TRUNCATE if you want to actually destroy data. I will go with that unless we have other objections. > BTW, I would have also used such a feature on multiple occasions in the > past and expect I would do in the future too. > > Cheers, > Csaba. > > -- Simon Riggs http://www.2ndQuadrant.com/books/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
