Re: CREATE INDEX and HOT - revised design - Mailing list pgsql-hackers

From Tom Lane
Subject Re: CREATE INDEX and HOT - revised design
Date
Msg-id 21023.1175273532@sss.pgh.pa.us
Whole thread Raw
In response to Re: CREATE INDEX and HOT - revised design  ("Florian G. Pflug" <fgp@phlo.org>)
Responses Re: CREATE INDEX and HOT - revised design  ("Pavan Deolasee" <pavan.deolasee@gmail.com>)
Re: CREATE INDEX and HOT - revised design  ("Florian G. Pflug" <fgp@phlo.org>)
List pgsql-hackers
"Florian G. Pflug" <fgp@phlo.org> writes:
> Tom Lane wrote:
>> I do not think you can assume that the plan won't be used later with
>> some older snapshot.

> So maybe we'd need to use the SerializableSnapshot created at the start
> of each transaction for this check, and not the ActiveSnapshot? Could
> that work?

That might work, but it doesn't seem to address the core objection:
there's no mechanism to cause the query to be replanned once the
snapshot is new enough, because no relcache inval will happen.  So
most likely existing backends will keep using old plans that don't
consider the index.
        regards, tom lane


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