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Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE - Mailing list pgsql-hackers

From Mark Dilger
Subject Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE
Date
Msg-id B3D5900B-4397-4F86-96EB-9EDA84F64129@enterprisedb.com
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In response to Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE  (Andres Freund <andres@anarazel.de>)
Responses Re: BUG: Postgres 14 + vacuum_defer_cleanup_age + FOR UPDATE + UPDATE
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> On Jan 9, 2023, at 11:34 AM, Andres Freund <andres@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 update_cached_xid_range(), we end up using the xid 0 (or an outdated value in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
theproblem exist in amcheck as currently committed, or are you thinking about a problem that arises only after applying
yourpatch?  I'm a bit fuzzy on where xid 0 gets used. 

Thanks

—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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