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Group replication system variables

variable name
group_replication_auto_evict_timeout
group_replication_certification_loop_chunk_size
group_replication_certification_loop_sleep_time
group_replication_flow_control_mode

group_replication_auto_evict_timeout

The variable is in tech preview mode. Before using the variable in production, we recommend that you test restoring production from physical backups in your environment, and also use the alternative backup method for redundancy.

Option Description
Command-line –group-replication-auto-evict-timeout
Dynamic Yes
Scope Global
Type Integer
Default value 0
Maximum Value 65535
Unit seconds

The value can be changed while Group Replication is running. The change takes effect immediately. Every node in the group can have a different timeout value, but, to avoid unexpected exits, we recommend that all nodes have the same value.

The variable specifies a period of time in seconds before a node is automatically evicted if the node exceeds the flow control threshold. The default value is 0, which disables the eviction. To set the timeout, change the value with a number higher than zero.

In single-primary mode, the primary server ignores the timeout.

group_replication_certification_loop_chunk_size

Option Description
Command-line –group-replication-certification-loop-chunk-size
Dynamic Yes
Scope Global
Data type ulong
Default value 0

Defines the size of the chunk that must be processed during the certifier garbage collection phase after which the client transactions are allowed to interleave. The default value is 0.

The minimum value is 0. The maximum value is 4294967295.

group_replication_certification_loop_sleep_time

Option Description
Command-line –group-replication-certification-loop-sleep-time
Dynamic Yes
Scope Global
Data type ulong
Default value 0

Defines the sleep time in microseconds that the certifier garbage collection loop allows client transactions to interleave. The default value is 0.

The minimum value is 0. The maximum value is 1000000.

group_replication_flow_control_mode

Option Description
Command-line –group_replication_flow_control_mode
Dynamic Yes
Scope Global
Data type Enumeration
Default value Quota
Valid values DISABLED
QUOTA
MAJORITY

The “MAJORITY” value is in tech preview mode. Before using the variable in production, we recommend that you test restoring production from physical backups in your environment, and also use the alternative backup method for redundancy.

The variable specifies the mode use for flow control.

Percona Server for MySQL adds the “MAJORITY” value to the group_replication_flow_control_mode variable. In “MAJORITY” mode, flow control is activated only if the majority, more than half the number of members, exceed the flow control threshold. The other values are not changed.

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Last update: 2023-10-26