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Re: snapshot too old issues, first around wraparound and then more. - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: snapshot too old issues, first around wraparound and then more.
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Msg-id CACjxUsMKLpDO_-A8p_oyp3FGdRc02we3=CopsicMk0ELm_XCpw@mail.gmail.com
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In response to Re: snapshot too old issues, first around wraparound and then more.  (Andres Freund <andres@anarazel.de>)
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On Wed, Apr 1, 2020 at 6:59 PM Andres Freund <andres@anarazel.de> wrote:
index fetches will never even try to
detect that tuples it needs actually have already been pruned away.

I looked at this flavor of problem today and from what I saw:

(1) This has been a problem all the way back to 9.6.0.
(2) The behavior is correct if the index creation is skipped or if enable_indexscan is turned off in the transaction, confirming Andres' analysis.
(3) Pruning seems to happen as intended; the bug found by Peter seems to be entirely about failing to TestForOldSnapshot() where needed.

--
Kevin Grittner
VMware vCenter Server
https://www.vmware.com/

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