Re: Conflict detection for update_deleted in logical replication

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Cc: vignesh C <vignesh21(at)gmail(dot)com>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, shveta malik <shveta(dot)malik(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Conflict detection for update_deleted in logical replication
Date: 2025-01-16 10:31:47
Message-ID: CAA4eK1+nf=zBLq75w9yYUw+HL5OvFfgRfeM8yNNpEjo2pLARLg@mail.gmail.com
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On Thu, Jan 16, 2025 at 3:45 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Fri, Jan 3, 2025 at 4:31 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> On Thu, Jan 2, 2025 at 2:57 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>> >
>> > Conflict detection of truncated updates is detected as update_missing
>> > and deleted update is detected as update_deleted. I was not sure if
>> > truncated updates should also be detected as update_deleted, as the
>> > document says truncate operation is "It has the same effect as an
>> > unqualified DELETE on each table" at [1].
>> >
>>
>> This is expected behavior because TRUNCATE would immediately reclaim
>> space and remove all the data. So, there is no way to retain the
>> removed row.
>
>
> I’m not sure whether to call this expected behavior or simply acknowledge that we have no way to control it. Logically, it would have been preferable if it behaved like a DELETE, but we are constrained by the way TRUNCATE works.
>

I see your point. So, it is probably better to add a Note about this.

--
With Regards,
Amit Kapila.

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