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From: Andreas Karlsson <[email protected]>
To: vellaipandiyan sm <[email protected]>
To: [email protected]
Subject: Re: Review observations for partial REFRESH MATERIALIZED VIEW patc
Date: Tue, 19 May 2026 11:59:54 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAGXjcjkHK8kNeTPzcvDDVZ_rjV4FwPFCncvwhhpOZooWa_VD1g@mail.gmail.com>
References: <CAGXjcjkHK8kNeTPzcvDDVZ_rjV4FwPFCncvwhhpOZooWa_VD1g@mail.gmail.com>

On 5/19/26 7:42 AM, vellaipandiyan sm wrote:
> I reviewed the REFRESH MATERIALIZED VIEW ... WHERE patch and had a few 
> questions around concurrency semantics.
> 
>   * The original DELETE -> INSERT approach exposing a consistency gap
>     makes sense, especially once tuple locks disappear after DELETE. The
>     newer FOR UPDATE + single-CTE approach seems safer, though I wonder
>     whether overlapping refreshes could still encounter deadlock
>     scenarios around UPSERT conflicts.
>   * The CONCURRENTLY behavior also feels somewhat unintuitive here. With
>     WHERE refreshes, the non-CONCURRENT path appears more permissive for
>     writers than CONCURRENTLY WHERE, which seems opposite to the
>     expectation established by normal REFRESH MATERIALIZED VIEW semantics.
>   * It may also help to document the intended guarantees around
>     overlapping partial refreshes and concurrent DML on base tables.

Hi,

Thanks for the review, but please reply-all to the original thread when 
you review a patch so the original author and previous reviewers can see 
your review.

If you do not have the original email thread you can go into the archive 
and request it to be sent to you so you can reply to it.

You can click the "Resend email" link at 
https://www.postgresql.org/message-id/CAA4eK1KSEL%2Bb81L47MpdVCY79n0QgboxF6XTEjSc0ZcLkDzyWQ%40mail.g...

-- 
Andreas Karlsson
Percona

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