The number of days that binary log files are kept before the server deletes them automatically. Without a limit, logs will grow until they fill up the disk. For point-in-time recovery the retention period must be at least as long as the interval between full backups, so that all transactions since the last backup remain available for replay.

A value of `0` disables automatic deletion entirely. Fractions of a day like `0.5` are supported on MySQL 8 and MariaDB 10.6 or later. MariaDB always limits retention to 99 days, while MySQL 8 accepts up to 49710 days.