Innodb Cluster FAQs

1. When you invoke shell.connect('clusterusr@node1:3306') it does not ask password from second time . Why is it so ? Where does Innodb cluster save its passwords ?

It stores the password in vault (similar to what config_editor does) during the first connection . From second connection it does not prompt for password

You can use mysql_config_editor --print all to check what is already stored

2. Can we use 2 nodes in Innodb cluster instead of 3 nodes ?

It is recommended to have odd number of nodes .In order to be able to avoid split brain, a cluster needs an odd number of members.
So start with 3 nodes to avoid any split-brain situations

3. Router Vs ProxySQL - What is the difference ?

ProxySQL supports query routing (read/write splitting) , query caching etc.. It is level 7 proxy where as router is level 3

4. How to change primary node ?

5. Which ports need to be open for Innodb cluster ?

3306 --> MySQL port 33060 --> MySQL X port 33061 --> Group replication communication port

6. How do you check the status of Innodb cluster - How to know the primary node ?

To find out which server is currently the primary when deployed in single-primary mode, use the MEMBER_ROLE column in the performance_schema.replication_group_members table. For example:

mysql> SELECT MEMBER_HOST, MEMBER_ROLE FROM performance_schema.replication_group_members;
+-------------------------+-------------+
| MEMBER_HOST             | MEMBER_ROLE |
+-------------------------+-------------+
| remote1.example.com     | PRIMARY     |
| remote2.example.com     | SECONDARY   |
| remote3.example.com     | SECONDARY   |
+-------------------------+-------------+

7. How to stop/start Innodb cluster for maintenance ?

8. How to identify the node that is ahead of other members ?

9. What are some of the limitations of Innodb cluster ?

10. What engines are supported by Innodb cluster ?