No need to change the default transaction isolation level globally on a server

At least since Nextcloud 8.1 this is automatically set on each DB connection (cf. nextcloud/server@bcf65d9).

Signed-off-by: Sven Strickroth <email@cs-ware.de>

Author: csware

admin_manual/configuration_database/linux_database_configuration.rst

@@ -20,36 +20,19 @@ requires that you install and set up the server software first.
   scope of this document.  Please refer to the documentation for your specific
   database choice for instructions.
 
-.. _db-transaction-label:
-
-Database "READ COMMITTED" transaction isolation level
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-As discussed above Nextcloud is using the ``TRANSACTION_READ_COMMITTED`` transaction isolation
-level. Some database configurations are enforcing other transaction isolation levels. To avoid
-data loss under high load scenarios (e.g. by using the sync client with many clients/users and
-many parallel operations) you need to configure the transaction isolation level accordingly.
-Please refer to the `MySQL manual <https://dev.mysql.com/doc/refman/5.7/en/set-transaction.html>`_
-for detailed information.
-
-Parameters
-----------
-For setting up Nextcloud to use any database, use the instructions in :doc:`../installation/installation_wizard`. You should not have to edit the respective values in the :file:`config/config.php`.  However, in special cases (for example, if you want to connect your Nextcloud instance to a database created by a previous installation of Nextcloud), some modification might be required.
-
 Configuring a MySQL or MariaDB database
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 If you decide to use a MySQL or MariaDB database, ensure the following:
 
-* The transaction isolation level is set to "READ-COMMITTED" in your MariaDB server configuration :file:`/etc/mysql/my.cnf` to persist even after a restart of your database server.
+* The **binlog_format** is set to "ROW" or "MIXED" ("MIXED" is the default since MariaDB 10.2.4) in your MariaDB server configuration :file:`/etc/mysql/my.cnf` to persist even after a restart of your database server.
 
-  Verify the **transaction_isolation** and **binlog_format**:
+  Verify the **binlog_format**:
 
 ::
 
   [mysqld]
   ...
-  transaction_isolation = READ-COMMITTED
   binlog_format = ROW
   ...
 
@@ -84,7 +67,6 @@ Your :file:`/etc/mysql/my.cnf` could look like this:
   [mysqld]
   character_set_server = utf8mb4
   collation_server = utf8mb4_general_ci
-  transaction_isolation = READ-COMMITTED
   binlog_format = ROW
   innodb_large_prefix=on
   innodb_file_format=barracuda

admin_manual/configuration_server/security_setup_warnings.rst

@@ -124,11 +124,3 @@ Some files have not passed the integrity check
 ----------------------------------------------
 
 Please refer to the :ref:`code_signing_fix_warning_label` documentation how to debug this issue.
-
-Your database does not run with "READ COMMITED" transaction isolation level
----------------------------------------------------------------------------
-
-"Your database does not run with "READ COMMITED" transaction isolation level.
-This can cause problems when multiple actions are executed in parallel."
-
-Please refer to :ref:`db-transaction-label` how to configure your database for this requirement.

admin_manual/installation/system_requirements.rst

@@ -54,8 +54,7 @@ Database requirements for MySQL / MariaDB
 The following is currently required if you're running Nextcloud together with a MySQL / MariaDB database:
 
 * InnoDB storage engine (MyISAM is not supported)
-* "READ COMMITED" transaction isolation level (See: :ref:`db-transaction-label`)
-* Disabled or BINLOG_FORMAT = ROW configured Binary Logging (See: https://dev.mysql.com/doc/refman/5.7/en/binary-log-formats.html)
+* Disabled, BINLOG_FORMAT = ROW or BINLOG_FORMAT = MIXED configured Binary Logging (See: https://dev.mysql.com/doc/refman/5.7/en/binary-log-formats.html)
 * For **Emoji (UTF8 4-byte) support** see :doc:`../configuration_database/mysql_4byte_support`
 
 Desktop client