We are doing tests with MariaDB 10.6 testing to deploy it on our production enviroment.

But, in our testing we have some wrong expirence with the undo purge process.

We did the test with sysbench tool:

{{sysbench \
--db-driver=mysql \
--mysql-user=sbtest_user \
--mysql_password=user_test \
--mysql-db=sbtest \
--mysql-host=mariadb-dba-test-01 \
--mysql-port=33033 \
--tables=32 \
--table-size=1000000 \
/usr/share/sysbench/oltp_read_write.lua prepare

sysbench \
--db-driver=mysql \
--mysql-user=sbtest_user \
--mysql_password=user_test \
--mysql-db=sbtest \
--mysql-host=mariadb-dba-test-00 \
--mysql-port=33033 \
--tables=32 \
--table-size=1000000 \
--threads=8 \
--time=0 \
--events=0 \
--report-interval=1 \
/usr/share/sysbench/oltp_read_write.lua run}}

After many tests an reads we found this pool of variables to set:

innodb_purge_threads = 32
innodb_purge_batch_size = 50
innodb_max_undo_log_size = 1G
innodb_purge_rseg_truncate_frequency = 64
innodb_undo_log_truncate = on

But, the problem was the same.

We didn't see the same behaivor wth MariaDB 10.5 version.

Executing this query:

select count from information_schema.innodb_metrics where name = 'trx_rseg_history_len';

The values never stop to increase.