can database size be different on different node in mairadb galera cluster?

Question

I have three node MariaDB Galera Cluster. Initially database size in all the three nodes was same. However recently it has been noticed that database size in one node more than other two node. Could you please let me know whether it is expected behaviour.

Thanks in advance.

Answer 1

As Galera doesn't do physical replication of tablespace disk blocks but logical replication of transactions the data sizes on different nodes (assuming you are referring to tablespace file sizes on disk) may differ for several reasons:

• differences in table/index fragmentation due to different operations order
• different undo log sizes due to local rollbacks never replicated to other nodes
• ... or due to different multi-versioning requirements as old row stats needed to be preserved longer for long running transactions still needing an older isolated view of the data
• ...

So this is expected behavior for sure.