Re: MultiXact bugs

On 2013-11-29 22:27:16 +0100, Andres Freund wrote:
> Looking at predicate.c I think I see a bigger problem though: Isn't its
> usage of HeapTupleSatisfiesVacuum() quite dangerous? It passes
> TransactionXmin to HeapTupleSatisfiesVacuum(). But since that's just the
> transaction's own cutoff, not the global cutoff that will cause wrong
> hint bits to be set. Or am I missing something?
> HTSV's comment says:
>  *
>  * OldestXmin is a cutoff XID (obtained from GetOldestXmin()).    Tuples
>  * deleted by XIDs >= OldestXmin are deemed "recently dead"; they might
>  * still be visible to some open transaction, so we can't remove them,
>  * even if we see that the deleting transaction has committed.
>  */

Strike that, sorry for the noise. I was thinking there was some
conditional hint bit setting based on OldestXmin in there, but I was
misremembering.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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