What are the defects of Percona XtraDB Cluster

Editor to share with you what are the defects of Percona XtraDB Cluster, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

The Cluster of Percona is actually based on the Galera implementation, adding some parameters of mysql and calling the API of Galera. The overall workflow is as follows:

1. Client submits MySQL database access request

two。 Use wsrepAPI to call Galera to copy data changes to other nodes in the cluster

The defects are as follows:

1. It works on InnoDB engine tables by default, so it doesn't support other engines' tables very well or even at all, so don't consider using MyISAM or other storage engines on PXC.

two。 All tables must have a primary key

3. Unsupported operations: LOCK/UNLOCK TABLES, lock functions (GET_LOCK (), RELEASE_LOCK (). )

4.query log logs cannot be stored in a table, they must be stored in a file

5. Since clustering is based on optimistic concurrency control (optimistic concurrency control), transaction conflicts may occur during the commit phase.

6. XA transactions are not supported because it is possible for XA transactions to have an exception and rollback during commit

7. The throughput / performance of the entire cluster depends on the slowest node (cost)

8. The minimum recommended number of cluster nodes is 3, otherwise it is easy to produce brain fissure (cost)

9. It is expensive to add new nodes, and there are as many duplicated data as there are as many nodes.

10. Can not effectively solve the write scaling problem, all write operations will occur on all nodes

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