Hello Stefano,
If *all* of your user tables (those not located in a system database) are using the InnoDB storage engine, then the option --single-transaction could do that for you.
The system databases are: mysql, information_schema, performance_schema, and sys.
Even if all of your "user" tables are InnoDB, if you are changing any binlogged non-InnoDB tables while you are in the middle of your backup (such as creating or adjusting any user accounts which needs to change at least one MyISAM table in the `mysql` database) then you must take locks in order to make your backup transactionally consistent with one single location in the Binary Log.
Yours,
--
Shawn Green
MySQL Senior Principal Technical Support Engineer
Oracle USA, Inc. - Integrated Cloud Applications & Platform Services
Office: Blountville, TN
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