wsrep_osu_method

USAGE

DETAILS

The wsrep_osu_method system variable has the following supported values:

Value

Description

TOI

  • This method uses "Total Order Isolation" mode.

  • In TOI mode, the DDL statement only needs to be executed on a single cluster node, and the cluster node will replicate it to all other cluster nodes. All of the cluster nodes will execute the DDL statement at the same location in the replication stream to ensure consistency. The TOI method is very safe, but it can result in more locking than other modes.

  • TOI is the default mode.

RSU

  • This method uses "Rolling Schema Upgrade" mode.

  • In RSU mode, the DDL statement needs to be executed on each cluster node separately. If the DDL statement causes the table to change in a way that is not backward-compatible for replication purposes, then RSU mode can lead to replication errors. Therefore, it is only recommended to use RSU mode if the specific schema change is backward-compatible for replication purposes or if write activity for the specific table has been stopped.

NBO

  • This method uses "Non-Blocking Operations" mode.

  • NBO mode is supported in MariaDB Enterprise Server 10.5 and later.

  • In NBO mode, the DDL statement only needs to be executed on a single cluster node, and the cluster node will replicate it to all other cluster nodes. All of the cluster nodes will execute the DDL statement at the same location in the replication stream to ensure consistency. In this way, it is similar to TOI. However, NBO mode uses much more efficient locking for some operations than TOI does.

SYNONYMS

SCHEMA

PARAMETERS

Command-line

--wsrep_osu_method[={TOI|RSU|NBO}]

Configuration file

Supported

Dynamic

Yes

Scope

Global, Session

Data Type

ENUM (TOI, RSU, NBO)

Product Default Value

TOI

SKYSQL

PRIVILEGES

EXAMPLES

ERROR HANDLING

FEATURE INTERACTION

RESPONSES

DIAGNOSIS

ISO 9075:2016

CHANGE HISTORY

Release Series

History

23.08 Enterprise

  • Present starting in MariaDB Enterprise Server 23.08.0.

23.07 Enterprise

  • Present starting in MariaDB Enterprise Server 23.07.0.

10.6 Enterprise

  • Present starting in MariaDB Enterprise Server 10.6.4-1.

10.6 Community

  • Present starting in MariaDB Community Server 10.6.0.

10.5 Enterprise

  • Present starting in MariaDB Enterprise Server 10.5.3-1.

10.5 Community

  • Present starting in MariaDB Community Server 10.5.0.

10.4 Enterprise

  • Present starting in MariaDB Enterprise Server 10.4.6-1.

10.4 Community

  • Present starting in MariaDB Community Server 10.4.0.

10.3 Enterprise

  • Present starting in MariaDB Enterprise Server 10.3.16-1.

10.3 Community

  • Present starting in MariaDB Community Server 10.3.0.

10.2 Enterprise

  • Present starting in MariaDB Enterprise Server 10.2.25-1.

10.2 Community

  • Present starting in MariaDB Community Server 10.2.0.

EXTERNAL REFERENCES