pg_receivewal starting position

From: Ronan Dunklau <ronan(dot)dunklau(at)aiven(dot)io>
To: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: pg_receivewal starting position
Date: 2021-07-27 05:50:39
Message-ID: 18708360.4lzOvYHigE@aivenronan
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers


I've notived that pg_receivewal logic for deciding which LSN to start
streaming at consists of:
- looking up the latest WAL file in our destination folder, and resume from
- if there isn't, use the current flush location instead.

This behaviour surprised me when using it with a replication slot: I was
expecting it to start streaming at the last flushed location from the
replication slot instead. If you consider a backup tool which will take
pg_receivewal's output and transfer it somewhere else, using the replication
slot position would be the easiest way to ensure we don't miss WAL files.

Does that make sense ?

I don't know if it should be the default, toggled by a command line flag, or if
we even should let the user provide a LSN.

I'd be happy to implement any of that if we agree.

Ronan Dunklau


Browse pgsql-hackers by date

  From Date Subject
Next Message Dilip Kumar 2021-07-27 05:58:32 Re: [bug?] Missed parallel safety checks, and wrong parallel safety
Previous Message Andrey V. Lepikhov 2021-07-27 05:34:30 Re: Removing unneeded self joins