gcs.fc_limit

Overview

Pause replication if recv queue exceeds this number of writesets

The wsrep_provider_options system variable applies to MariaDB Enterprise Cluster, powered by Galera and to Galera Cluster available with MariaDB Community Server. This page relates specifically to the gcs.fc_limit wsrep_provider_options.

See also: wsrep Provider Options for MariaDB Enterprise Server 23.08, in 23.07 ES, in 10.6 ES, in 10.5 ES, in 10.4 ES, in 10.3 ES, in 10.2 ES, in 10.6 CS, in 10.5 CS, in 10.4 CS, in 10.3 CS, and in 10.2 CS

USAGE

DETAILS

The gcs.fc_limit option is used for replication flow control. Replication is paused when the replica queue exceeds this limit.

Attribute

Value

Option Name

gcs.fc_limit

Default Value

16

Dynamic

YES

Debug

NO

SYNONYMS

SCHEMA

PARAMETERS

SKYSQL

PRIVILEGES

EXAMPLES

Display Current Value

wsrep_provider_options define optional settings the node passes to the wsrep provider.

To display current wsrep_provider_options values:

SHOW GLOBAL VARIABLES LIKE 'wsrep_provider_options';

The expected output will display the option and the value. Options with no default value, for example SSL options, will not be displayed in the output.

Set in Configuration File

When changing a setting for a wsrep_provider_options in the config file, you must list EVERY option that is to have a value other than the default value. Options that are not explicitly listed are reset to the default value.

Options are set in the my.cnf configuration file. Use the ; delimiter to set multiple options.

The configuration file must be updated on each node. A restart to each node is needed for changes to take effect.

Use a quoted string that includes every option where you want to override the default value. Options that are not in the list will reset to their default value.

To set the option in the configuration file:

wsrep_provider_options='gcs.fc_limit=19;gcache.debug=YES;gcs.fc_limit=NO;socket.send_buf_size=NO;evs.keepalive_period=PT3S'

Set Dynamically

Changes made dynamically with SET GLOBAL are not durable and will be lost when the server is stopped. To be durable, changes must be set in the configuration file.

The gcs.fc_limit option can be set dynamically using the SET GLOBAL command. Setting wsrep_provider_options dynamically does not change the value of other wsrep_provider_options.

To set gcs.fc_limit dynamically:

SET GLOBAL wsrep_provider_options='gcs.fc_limit=19';

To dynamically set multiple options in a single statement:

SET GLOBAL wsrep_provider_options='gcs.fc_limit=19;cert.optimistic_pa=NO';

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