Today i checked my MaridDB configuration file (50-server.cnf) and compared them with the nextcloud recommendations.
I found some missing settings.
Now i have to add or change the following directives:
transaction_isolation = READ-COMMITTED
binlog_format = ROW
innodb_flush_log_at_trx_commit = 2
innodb_log_buffer_size = 32M
innodb_max_dirty_pages_pct = 90
Can these settings be set retrospectively without great risk?