On 2024-12-13 14:53, Kazuhiko via discuss wrote:
Here is the summary for history length issue:
(RC = READ COMMITTED, RR = REPEATABLE READ)
Good
* 10.4, RR only with innodb_locks_unsafe_for_binlog
* 10.4, RC for DML, RR for DQL
* 10.5, RC only
Bad
* 10.5, RC for DML, RR for DQL
* 11.4, RC for DML, RR for DQL
Could you please also test the recent 10.6.20 release? It includes
some performance improvements to the InnoDB undo log subsystem that
were not applied to the 10.5 series, most recently MDEV-34515.
In 'RC for DML, RR for DQL' combination, here are the more detailed
list
for history length issue :
Good
* 10.4.34
* 10.5.5, 10.5.16, 10.5.19, 10.5.20
* 10.6.13
Bad
* 10.5.21, 10.5.22, 10.5.27
* 10.6.15, 10.6.20
* 11.4.3, 11.4.4
So it seems that the changes between 10.5.20 and 10.5.21 caused this
issue.
# I skipped 10.6.14 because of the warning in the release note.
# https://mariadb.com/kb/en/mariadb-10-6-14-release-notes/
Sorry, 10.6.13 seems 'not always' good.
I tried 10.6.13 with 4GB log file and 256MB log file cases (buffer pool
size is 16GB on both tests).
No history length increase issue on 10.6.13 with 4GB log file.
BUT quite bad behaviour on 10.6.13 with 256MB log file, i.e. some
history length caused by cleanup
process still remained at the beginning, and increased history length
remained even after everything
finished. Also 1-2 seconds stall happened several times.
(see the attached graphs)
On 10.5.20, I had no such issue on both 4GB log file and 256MB log file,
and its behaviour was quite
10.4.34.
Best regards,
Kazuhiko
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