Replica state

Job details

Name:	Replica state
Platform:	Mysql
Category:	Cluster and Replication
Description:	NDB data node status
Long description:
Version:	1.2
Default schedule:	60s
Requires engine install:	No
Compatibility tag:	./instance[databasetype=‘mysql’]

Name	Default value	Description
return_status	1	Return status value (ALARM – 2, WARNING – 1, or OK – 0) when replica changes occurs.
keep_status	10	For how long (in minutes) the jobs status will be kept when replica changes occurs.

Purpose: The purpose of this job is to monitor and track if replica changes occur in MySQL database instances. It observes if an instance becomes a replica or if an instance ceases to be a replica.
Why: Monitoring replica state is essential in a database context, as it helps in keeping track of the replica status of each MySQL database instance. It aids in identifying shifts in database roles and maintaining a balanced distribution of the load.
Manual checking: This job cannot be manually checked as it entails complex scripting and continuous monitoring only possible through this dbWatch Control Center job.

The job, titled “Replica state”, is version 1.2, developed by the dbwatch.no company.
It belongs to the group com.dbwatch.job and holds the artifact id mysql_replica_state.
It records keys such as status, details, last_replicas_state, last_replicas_state_time, and last_replicas_state_time_count.
This job falls under the category of “Cluster and Replication”.
Its default scheduling frequency is every 60 seconds.

The JavaScript engine behind this job performs the following functions:

It sets initial values for variables including status, pos, msg, replicas_stat, time_sec, change_val, sec_after_last_change, change_count_val.
It retrieves the master/slave status.
It checks if replica changes have occurred and updates values of ‘last_replicas_state_time’ and ‘last_replicas_state_time_count’ and ‘status’ accordingly.
It checks if the instance is running as a slave (replica) or master (source) host, and provides the time of the last change in each case.
It maintains status and updates messages if a change from MASTER to REPLICA or REPLICA to MASTER is detected.
It catches and reports exceptions during execution.

The report template contains a version of 2, with the title “Replica state” and description “Master/Slave change.”
A default scheduling of “0 * * *” is set.
The chapter presentation consist of a table presentation with column name “Details”.
It displays the status between the replication SQL (applier) thread and the replication I/O (receiver) thread.