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I have a Percona/Galera cluster and see this when i monitor the different cluster nodes. What does this really mean? And is this something erroneous that needs to be taken care of?

This is how one of the nodes looks like.

Thanks in advance.

Cluster node 1

All other nodes in the cluster looks like this The other cluster nodes

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  • One factor could be tables opened for reading, which would only be opened on the server being queried. Another could be writes that were rolled back, since Galera replicates transactions among servers at commit time, not before.
    – Michael - sqlbot
    Commented Jan 5, 2016 at 13:01

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You are writing to the 'one' node? That is, you are treating it as the only Master? Galera does "Row Based Replication", so it probably does not need to open the table definition on the 'Slaves'?

Do you have the same values for SHOW VARIABLES LIKE 'table%'; on all nodes?

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  • Yep, they are exactly the same. Well it could have been that one we bootstrapped the cluster with.
    – Fred Asp
    Commented Jan 7, 2016 at 7:22
  • Are all writes going to one node?
    – Rick James
    Commented Jan 7, 2016 at 7:26
  • Otherwise they are all load balanced so number of connections should be similar for all the nodes.
    – Fred Asp
    Commented Jan 7, 2016 at 7:28
  • "Connections" and "tables opened" are separate things.
    – Rick James
    Commented Jan 7, 2016 at 7:31
  • I might have found it. Could a SHOW CREATE TABLE spark a 'Table Definitions Opened'?
    – Fred Asp
    Commented Jan 7, 2016 at 8:33

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