Re: Support for REINDEX CONCURRENTLY

Bruce Momjian <bruce@momjian.us> writes:
> On Thu, Jan 24, 2013 at 01:29:56PM -0500, Robert Haas wrote:
>> I'm kind of unconvinced of the value proposition of this patch.  I
>> mean, you can DROP INDEX CONCURRENTLY and CREATE INDEX CONCURRENTLY
>> today, so ... how is this better?

> This has been on the TODO list for a while, and I don't think the
> renaming in a transaction work needed to use drop/create is really
> something we want to force on users.  In addition, doing that for all
> tables in a database is even more work, so I would be disappointed _not_
> to get this feature in 9.3.

I haven't given the current patch a look, but based on previous
discussions, this isn't going to be more than a macro for things that
users can do already --- that is, it's going to be basically DROP
CONCURRENTLY plus CREATE CONCURRENTLY plus ALTER INDEX RENAME, including
the fact that the RENAME step will transiently need an exclusive lock.
(If that's not what it's doing, it's broken.)  So there's some
convenience argument for it, but it's hardly amounting to a stellar
improvement.

I'm kind of inclined to put it off till after we fix the SnapshotNow
race condition problems; at that point it should be possible to do
REINDEX CONCURRENTLY more simply and without any exclusive lock
anywhere.
        regards, tom lane