Each member in a replication group certifies and applies
transactions committed by the group. Statistics regarding the
certifier and applier procedures are useful to understand how the
applier queue is growing, how many conflicts have been found, how
many transactions were checked, which transactions are committed
everywhere, and so on. The table
provides the following information related to the certification
Table 17.1 replication_group_member_stats
The name of the Group Replication channel.
This gives the member server UUID to which we are currently connected to. This has a different value for each member in the group. This also serves a key since it is unique to each member.
Number of transactions in queue pending conflict detection checks. Once checked for conflicts, and if they pass the check, they are queued to be applied as well.
Indicates the number of transactions that were checked for conflicts.
Indicates the number of transactions that did not pass the conflict detection check.
Indicates the current size of the conflict detection database (against which each transaction is certified).
Indicates those transactions that have been successfully committed on all members of the current view. This is updated at a fixed time interval.
Shows the transaction identifier of the last conflict free transaction checked.
These fields are important for monitoring the performance of the members connected in the group. For example, suppose that one of the group’s members is delayed and is not able to keep up to date with the other members of the group. In this case you might see a large number of transactions in the queue. Based on this information, you could decide to either remove the member from the group or delay the processing of transactions on the other members of the group thus reducing the number of queued transactions. This information can can also help you to decide how to adjust the flow control of the Group Replication plugin.