Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE

[Mark Dilger]

> On Jan 9, 2023, at 11:34 AM, Andres Freund <and...@anarazel.de> wrote:
> 
> 1) Because ctx->next_xid is set after the XidFromFullTransactionId() call in
> update_cached_xid_range(), we end up using the xid 0 (or an outdated value in
> subsequent calls) to determine whether epoch needs to be reduced.

Can you say a bit more about your analysis here, preferably with pointers to 
the lines of code you are analyzing?  Does the problem exist in amcheck as 
currently committed, or are you thinking about a problem that arises only after 
applying your patch?  I'm a bit fuzzy on where xid 0 gets used.

Thanks

—
Mark Dilger
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