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

> On Mar 8, 2023, at 4:15 PM, Andres Freund <andres@anarazel.de> wrote:
>
> I worked some more on the fixes for amcheck, and fixes for amcheck.
>
> The second amcheck fix ends up correcting some inaccurate output in the tests
> - previously xids from before xid 0 were reported to be in the future.
>
> Previously there was no test case exercising exceeding nextxid, without
> wrapping around into the past. I added that at the end of
> 004_verify_heapam.pl, because renumbering seemed too annoying.
>
> What do you think?

The changes look reasonable to me.

> Somewhat random note:
>
> Is it intentional that we VACUUM FREEZE test ROWCOUNT times? That's
> effectively O(ROWCOUNT^2), albeit with small enough constants to not really
> matter. I don't think we need to insert the rows one-by-one either. Changing
> that to a single INSERT and FREEZE shaves 10-12% off the tests.  I didn't
> change that, but we also fire off a psql for each tuple for heap_page_items(),
> with offset $N no less. That seems to be another 500ms.

I don't recall the reasoning.  Feel free to optimize the tests.

—
Mark Dilger
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