mysql pxc LIMITATIONS 8.0.19-10

1. Replication works only with InnoDB storage engine. Any writes to tables of other types are not replicated
2. Unsupported queries: LOCK TABLES and UNLOCK TABLES is not supported in multi-master setups Lock functions, such as GET_LOCK(), RELEASE_LOCK(), and so on
3. Query log cannot be directed to table. If you enable query logging, you must forward the log to a file:

log_output = FILE

Use general_log and general_log_file to choose query logging and the log file name.

4. Maximum allowed transaction size is defined by the wsrep_max_ws_rows and wsrep_max_ws_size
   wsrep_max_ws_rows：Defines the maximum number of rows each write-set can contain.
   最大允许值是 1048576。
   wsrep_max_ws_size： Defines the maximum write-set size (in bytes).
   值范围1024到2147483647
   LOAD DATA INFILE 每10000行或者更少提交一次，大事务使用LOAD DATA INFILE 会被拆分成很多小事务
   禁用特性：
   It doesn’t work as expected with autocommit=0 when enabled.
5. Transaction issuing COMMIT may still be aborted at that stage. 在PXC中，两个事务写入相同的行并提交，只有一个事务能提交成功，失败的将中止，返回错误代码

(Error: 1213 SQLSTATE: 40001 (ER_LOCK_DEADLOCK)).

6. XA transactions are not supported. 提交时有可能回滚
   https://dev.mysql.com/doc/refman/8.0/en/xa.html
7. 集群的写吞吐量受到最弱的节点的限制。推荐至少3个节点， 第三个节点可以是仲裁的节点
8. enforce_storage_engine=InnoDB is not compatible with wsrep_replicate_myisam=OFF wsrep_replicate_myisam is set to OFF by default
   参考： https://bugs.launchpad.net/percona-xtradb-cluster/+bug/1435482
9. 避免 ALTER TABLE … IMPORT/EXPORT It can lead to node inconsistency if not executed in sync on all nodes.
10. All tables must have a primary key . The DELETE statement is not supported on tables without a primary key.

Node Host IP
1 pxc1 172.16.0.61
1 pxc2 172.16.0.62
1 pxc3 172.16.0.63
Note: Avoid creating a cluster with two or any even number of nodes, because this can lead to split brain. For more information, see Cluster Failover