MIME-Version: 1.0
From: Fujii Masao <masao.fujii@gmail.com>
Date: Mon, 23 Mar 2026 17:23:23 +0900
Message-ID: 
 <CAHGQGwGTyHgtD9tyN664x6vQ8Q1G53H7ZUCgBU9_X=nLt3f1QA@mail.gmail.com>
Subject: Reduce log level of some logical decoding messages to DEBUG1
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Content-Type: multipart/mixed; boundary="000000000000462f15064dacc0ec"
Archived-At: 
 <https://www.postgresql.org/message-id/CAHGQGwGTyHgtD9tyN664x6vQ8Q1G53H7ZUCgBU9_X%3DnLt3f1QA%40mail.gmail.com>
Precedence: bulk

--000000000000462f15064dacc0ec
Content-Type: text/plain; charset="UTF-8"

Hi,

In logical decoding, messages like the following are currently logged at
LOG level:

    LOG:  starting logical decoding for slot "myslot"
    DETAIL:  Streaming transactions committing after 0/030872C0,
reading WAL from 0/03087288.
    STATEMENT:  ...
    LOG:  logical decoding found consistent point at 0/03087288
    DETAIL:  There are no running transactions.
    STATEMENT:  ...

These can be useful for debugging, but DBAs are typically not interested in
them. They can also be emitted frequently, for example, on each call to
functions like pg_logical_slot_peek_binary_changes() or
pg_replication_slot_advance() etc. When such functions are called repeatedly,
the logs can quickly become noisy.

The slotsync worker can also generate these messages periodically. Due to
the issue discussed at [1], this can currently happen as often as every 200ms
(which should be fixed separately). Even without that issue, these messages
would be still emitted regularly.

Given that these are mostly developer-oriented messages, logging them at
LOG level seems too verbose. I'm proposing to reduce their level to DEBUG1.
A patch is attached.

Alternatively, if we want to keep them at LOG by default, we could introduce
a GUC like trace_logical_decoding_messages, similar to
the old trace_recovery_messages, to control their verbosity independently
of log_min_messages.

Thought?

This topic came up in [1] and [2], and Amit suggested discussing it separately,
so I started this thread.

Regards,

[1] https://postgr.es/m/CAHGQGwF6zG9Z8ws1yb3hY1VqV-WT7hR0qyXCn2HdbjvZQKufDw@mail.gmail.com
[2] https://postgr.es/m/CAHGQGwED5kJxZ_MdCh=WLa5M7ekXdnzCO1ZCQhQNCEdfaEPwFQ@mail.gmail.com

-- 
Fujii Masao

--000000000000462f15064dacc0ec
Content-Type: application/octet-stream;
	name="v1-0001-Reduce-log-level-of-some-logical-decoding-message.patch"
Content-Disposition: attachment;
	filename="v1-0001-Reduce-log-level-of-some-logical-decoding-message.patch"
Content-Transfer-Encoding: base64
Content-ID: <f_mn2x4z040>
X-Attachment-Id: f_mn2x4z040
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--000000000000462f15064dacc0ec--