← Back to team overview

maria-developers team mailing list archive

Re: Understanding binlog group commit (MDEV-232, MDEV-532, MDEV-25611, MDEV-18959)


On Tue, May 16, 2023 at 1:37 PM Andrei Elkin <andrei.elkin@xxxxxxxxxxx> wrote:
> Can you comment on chances for `flush_lsn` never advance to the value of
>  `write_lsn` when/because Innodb has nothing to commit (so at such a time
> RM (or PURGE or FLUSH LOGS that have been mentioned too) might be run)?

If the last write to the log was an InnoDB internal one, it could be
done by log_write_up_to(lsn, false).
The log_sys.flushed_to_disk_lsn would only be advanced (to somewhere
closer to log_sys.lsn) if there was a subsequent call to
log_write_up_to(lsn, true).
Log checkpoint would advance log_sys.flushed_to_disk_lsn, as should a
user transaction commit. This could be a possible explanation.
Marko Mäkelä, Lead Developer InnoDB
MariaDB plc