MySQL :: MySQL 8.4 Reference Manual :: 29.12.11.10 The replication_group_communication_information Table (original) (raw)

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29.12.11.10 The replication_group_communication_information Table

This table shows group configuration options for the whole replication group. The table is available only when Group Replication is installed.

Thereplication_group_communication_information table has these columns:

• WRITE_CONCURRENCY
  The maximum number of consensus instances that the group can execute in parallel. The default value is 10. SeeSection 20.5.1.3, “Using Group Replication Group Write Consensus”.
• PROTOCOL_VERSION
  The Group Replication communication protocol version, which determines what messaging capabilities are used. This is set to accommodate the oldest MySQL Server version that you want the group to support. SeeSection 20.5.1.4, “Setting a Group's Communication Protocol Version”.
• WRITE_CONSENSUS_LEADERS_PREFERRED
  The leader or leaders that Group Replication has instructed the group communication engine to use to drive consensus. For a group in single-primary mode with thegroup_replication_paxos_single_leader system variable set to ON and the communication protocol version set to 8.0.27 or later, the single consensus leader is the group's primary. Otherwise, all group members are used as leaders, so they are all shown here. SeeSection 20.7.3, “Single Consensus Leader”.
• WRITE_CONSENSUS_LEADERS_ACTUAL
  The actual leader or leader that the group communication engine is using to drive consensus. If a single consensus leader is in use for the group, and the primary is currently unhealthy, the group communication selects an alternative consensus leader. In this situation, the group member specified here can differ from the preferred group member.
• WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE
  Whether the replication group is capable of using a single consensus leader. 1 means that the group was started with the use of a single leader enabled (group_replication_paxos_single_leader = ON), and this is still shown if the value ofgroup_replication_paxos_single_leader has since been changed on this group member. 0 means that the group was started with single leader mode disabled (group_replication_paxos_single_leader = OFF), or has a Group Replication communication protocol version that does not support the use of a single consensus leader (prior to 8.0.27). This information is only returned for group members inONLINE or RECOVERING state.
• MEMBER_FAILURE_SUSPICIONS_COUNT
  The address of each group member paired with the number of times this member has been seen as suspect by the local node. This information is displayed in JSON format. For a group with three members, the value of this column should appear similar to what is shown here:

{  
  "d57da302-e404-4395-83b5-ff7cf9b7e055": 0,  
  "6ace9d39-a093-4fe0-b24d-bacbaa34c339": 10,  
  "9689c7c5-c71c-402a-a3a1-2f57bfc2ca62": 0  
}  

Thereplication_group_communication_information table has no indexes.

TRUNCATE TABLE is not permitted for thereplication_group_communication_information table.