On Sat, Dec 31, 2011 at 8:26 AM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Fri, Dec 30, 2011 at 10:20 PM, Peter Eisentraut <pete...@gmx.net> wrote: >> On ons, 2011-08-24 at 11:24 -0700, Daniel Farina wrote: >>> I was poking around at tablecmds and index.c and wonder if a similar >>> two-pass approach as used by CREATE INDEX CONCURRENTLY can be used to >>> create a DROP INDEX CONCURRENTLY, and if there would be any interest >>> in accepting such a patch. >> >> Hmm, it seems I just independently came up with this same concept. My >> problem is that if a CREATE INDEX CONCURRENTLY fails, you need an >> exclusive lock on the table just to clean that up. If the table is >> under constant load, you can't easily do that. So a two-pass DROP INDEX >> CONCURRENTLY might have been helpful for me. > > Here's a patch for this. Please review.
I don't see how setting indisvalid to false helps with this, because IIUC when a session sees indisvalid = false, it is supposed to avoid using the index for queries but still make new index entries when a write operation happens - but to drop an index, I think you'd need to get into a state where no one was using the index for anything at all. Maybe we need to change indisvalid to a "char" and make it three valued: c = being created currently, v = valid, d = being dropped concurrently, or something like that. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers