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MySQL Cluster SQL Node not synchronizing

Server Fault Asked by user2249803 on November 10, 2021

I am new to MySQL Cluster and am trying to setup a new cluster for our new application. Here is what I have set up on 5 CentOS 64 bit VM and got the cluster to work using MySQL Cluster 7.2. I am trying to test it and have some issues.

“I have successfully installed the Cluster with 5 nodes (2 Data, 1 Mgmt and 2 SQL Nodes). While testing the cluster I have hit on one scenario where I am stuck and cannot make it to work. Here is the screen shot of the Management Node displaying all cluster nodes:

ndb_mgm> show

Cluster Configuration

[ndbd(NDB)] 2 node(s)
id=2 @10.0.3.138 (mysql-5.5.30 ndb-7.2.12, Nodegroup: 0)
id=3 @10.0.3.83 (mysql-5.5.30 ndb-7.2.12, Nodegroup: 0, Master)

[ndb_mgmd(MGM)] 1 node(s)
id=1 @10.0.3.135 (mysql-5.5.30 ndb-7.2.12)

[mysqld(API)] 2 node(s)
id=4 @10.0.3.87 (mysql-5.5.30 ndb-7.2.12)
id=5 @10.0.3.22 (mysql-5.5.30 ndb-7.2.12)

ndb_mgm>
Here is the scenario:

While all nodes in the cluster are working as a part of my test I shut down one of the SQL Node 4 and while this node is offline, I drop a database which is part of the cluster databases on SQL Node 5. When I bring up the offline SQL Node 4 and rejoin to the cluster the dropped database still shows up. It should sync with the old cluster databases meaning the dropped database when the SQL Node 4 was offline should be removed from the cluster and should not show up on SQL Node 4. This is a real scenario that can happen.

Also, I am searching for MySQL Cluster Test document which describes these scenarios and cannot seem to find it. “

Any Help will be greatly appreciated.

Thanks

One Answer

I ran my test again and this is what I find:

1) I have 2 Sql Nodes A and B in my NDB Cluster with 2 databases test and test1. I take Sql Node A out (stop mysqld) from the cluster. 2) While the Sql Node A is not part of the cluster, I drop database test1 from Sql Node B. 3) Then I rejoin (start mysqld) Sql Node A to the cluster. I still see test1 on Sql Node A but Sql Node B does not have it because I dropped it.

So just to confirm this does not work, however when I drop/add tables to test1 and even in fact add/delete data in the tables, they are all synchronized/replicated. So this confirms that we cannot drop a database while a Sql Node is out of the cluster and expect to be re synchronized to the node which was not part of the cluster when such drop occurred.

Answered by user2249803 on November 10, 2021

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