Re: Conflict detection and logging in logical replication

From: shveta malik <shveta(dot)malik(at)gmail(dot)com>
To: "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Jan Wieck <jan(at)wi3ck(dot)info>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, shveta malik <shveta(dot)malik(at)gmail(dot)com>
Subject: Re: Conflict detection and logging in logical replication
Date: 2024-08-21 03:39:32
Message-ID: CAJpy0uDUNigg86KRnk4A0KjwY8-pPaXzZ2eCjnb1ydCH48VzJQ@mail.gmail.com
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On Tue, Aug 20, 2024 at 4:45 PM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> Here are the remaining patches.
>
> 0001 adds additional doc to explain the log format.

Thanks for the patch. Please find few comments on 001:

1)
+<literal>Key</literal> (column_name, ...)=(column_name, ...);
existing local tuple (column_name, ...)=(column_name, ...); remote
tuple (column_name, ...)=(column_name, ...); replica identity
(column_name, ...)=(column_name, ...).

-- column_name --> column_value everywhere in right to '='?

2)
+ Note that for an
+ update operation, the column value of the new tuple may be NULL if the
+ value is unchanged.

-- Shall we mention the toast value here? In all other cases, we get a
full new tuple.

3)
+ The key section in the second sentence of the DETAIL line
includes the key values of the tuple that already exists in the local
relation for insert_exists or update_exists conflicts.

-- Shall we mention the key is the column value violating a unique
constraint? Something like this:
The key section in the second sentence of the DETAIL line includes the
key values of the local tuple that violates unique constraint for
insert_exists or update_exists conflicts.

4)
Shall we give an example LOG message in the end?

thanks
Shveta

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