Re: Support for REINDEX CONCURRENTLY - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Support for REINDEX CONCURRENTLY
Date
Msg-id 8984.1349737957@sss.pgh.pa.us
Whole thread Raw
In response to Re: Support for REINDEX CONCURRENTLY  (Jim Nasby <jim@nasby.net>)
Responses Re: Support for REINDEX CONCURRENTLY  (Jim Nasby <jim@nasby.net>)
Re: Support for REINDEX CONCURRENTLY  (Michael Paquier <michael.paquier@gmail.com>)
List pgsql-hackers
Jim Nasby <jim@nasby.net> writes:
> Yeah, what's the risk to renaming an index during concurrent access?

SnapshotNow searches for the pg_class row could get broken by *any*
transactional update of that row, whether it's for a change of relname
or some other field.

A lot of these problems would go away if we rejiggered the definition of
SnapshotNow to be more like MVCC.  We have discussed that in the past,
but IIRC it's not exactly a simple or risk-free change in itself.
Still, maybe we should start thinking about doing that instead of trying
to make REINDEX CONCURRENTLY safe given the existing infrastructure.
        regards, tom lane



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