Re: Fix stats reporting delays in logical parallel apply worker

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Fix stats reporting delays in logical parallel apply worker
Date: 2026-04-17 07:19:36
Message-ID: CAA4eK1JF-zny8pGP4Mafk8=mNBCV8A0a1-6HvVd1Q2ZVJW-NJw@mail.gmail.com
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On Fri, Apr 17, 2026 at 8:31 AM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> When implementing another feature, I noticed that parallel apply workers
> currently do not report statistics while idle in their main loop. This can cause
> stats from the last processed transaction to be arbitrarily delayed, especially
> when there are long gaps between streamed transactions.
>
> The issue is demonstrated in 0002, where a TAP test fails when attempting to
> collect stats from a parallel apply worker that has no subsequent transaction to
> trigger a stats report.
>
> 0001 fixes this issue by forcing a stats report when the worker is idle in the
> main loop, matching the behavior already present in LogicalRepApplyLoop() for
> regular logical apply workers.
>

LGTM. We should backpatch this change.

--
With Regards,
Amit Kapila.

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