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No need to change the default transaction isolation level globally on a server #9145

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No need to change the default transaction isolation level globally on a server #9145

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22 changes: 2 additions & 20 deletions admin_manual/configuration_database/linux_database_configuration.rst
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Expand Up @@ -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
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Hi, can we keep this section to have the transaction isolation level documented somewhere? I guess the rest can go.

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
...

Expand Down Expand Up @@ -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
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8 changes: 0 additions & 8 deletions admin_manual/configuration_server/security_setup_warnings.rst
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Expand Up @@ -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.
3 changes: 1 addition & 2 deletions admin_manual/installation/system_requirements.rst
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Expand Up @@ -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
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