Re: Add checkpoint and redo LSN to LogCheckpointEnd log message - Mailing list pgsql-hackers

From Bharath Rupireddy
Subject Re: Add checkpoint and redo LSN to LogCheckpointEnd log message
Date
Msg-id CALj2ACXDHGfhKkwzi81BRqWft4n85AO1zmkeqf6xEg+0xTCH9g@mail.gmail.com
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In response to Re: Add checkpoint and redo LSN to LogCheckpointEnd log message  (Fujii Masao <masao.fujii@oss.nttdata.com>)
Responses Re: Add checkpoint and redo LSN to LogCheckpointEnd log message  (Fujii Masao <masao.fujii@oss.nttdata.com>)
List pgsql-hackers
On Tue, Feb 1, 2022 at 9:10 AM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
> The order of arguments for LSN seems wrong. LSN_FORMAT_ARGS(ControlFile->checkPoint) should be specified ahead of
LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo)?

Thanks. Corrected.

> Could you tell me why the information for LSN is reported earlierly in the log message? Since ordinally users would
bemore interested in the information about I/O by checkpoint, the information for LSN should be placed later? Sorry if
thiswas already discussed. 

It is useful (for debugging purposes) if the checkpoint end message
has the checkpoint LSN(end) and REDO LSN(start). It gives more context
while analyzing checkpoint-related issues. The pg_controldata gives
the last checkpoint LSN and REDO LSN, but having this info alongside
the log message helps analyze issues that happened previously, connect
the dots and identify the root cause.

Regards,
Bharath Rupireddy.

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