The following limitations apply to Percona XtraDB Cluster:
Replication works only with InnoDB storage engine.
Any writes to tables of other types, including system (
are not replicated.
DDL statements are replicated in statement level,
and changes to
mysql.* tables will get replicated that way.
So you can safely issue
INSERT INTO mysql.user... will not be replicated.
You can enable experimental MyISAM replication support
UNLOCK TABLESis not supported in multi-master setups
RELEASE_LOCK(), and so on
Query log cannot be directed to table. If you enable query logging, you must forward the log to a file:
log_output = FILE
general_log_file to choose query logging
and the log file name.
Maximum allowed transaction size is defined by the
LOAD DATA INFILE processing will commit every 10 000 rows.
So large transactions due to
will be split to series of small transactions.
Due to cluster-level optimistic concurrency control,
COMMIT may still be aborted at that stage.
There can be two transactions writing to the same rows
and committing in separate Percona XtraDB Cluster nodes,
and only one of the them can successfully commit.
The failing one will be aborted.
For cluster-level aborts, Percona XtraDB Cluster gives back deadlock error code:
(Error: 1213 SQLSTATE: 40001 (ER_LOCK_DEADLOCK)).
XA transactions are not supported due to possible rollback on commit.
The write throughput of the whole cluster is limited by weakest node. If one node becomes slow, the whole cluster slows down. If you have requirements for stable high performance, then it should be supported by corresponding hardware.
The minimal recommended size of cluster is 3 nodes. The 3rd node can be an arbitrator.
InnoDB fake changes feature is not supported.
enforce_storage_engine=InnoDB is not compatible with
binlog_rows_query_log_events variable is not supported.
When running Percona XtraDB Cluster in cluster mode,
ALTER TABLE ... IMPORT/EXPORT workloads.
It can lead to node inconsistency if not executed in sync on all nodes.
For general inquiries about our open source software and database management tools, please send us your question and someone will contact you.