Re: Flaky vacuum truncate test in reloptions.sql

From: Arseny Sher <a(dot)sher(at)postgrespro(dot)ru>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Flaky vacuum truncate test in reloptions.sql
Date: 2021-03-30 13:22:18
Message-ID: 78aad736-c653-92fd-45ac-4482729459c6@postgrespro.ru
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On 3/30/21 10:12 AM, Michael Paquier wrote:

> Yep, this is the same problem as the one discussed for c2dc1a7, where
> a concurrent checkpoint may cause a page to be skipped, breaking the
> test.

Indeed, Alexander Lakhin pointed me to that commit after I wrote the
message.

> Why not just using DISABLE_PAGE_SKIPPING instead here?

I think this is not enough. DISABLE_PAGE_SKIPPING disables vm consulting
(sets
aggressive=true in the routine); however, if the page is locked and
lazy_check_needs_freeze says there is nothing to freeze on it, we again
don't
look at its contents closely.

-- cheers, arseny

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