PXC集羣參數之wsrep_on

修改wsrep_on參數值爲off，drop表，打開另外一個會話，發現表依舊存在。這個參數的主要做用是控制當前結點的寫入是否是要複製到其餘節點。與MySQL的sql_log_bin很類似。測試過程以下：

pxc01-->node1

mysql> show variables like 'wsrep_on';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_on      | ON    |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show status like 'wsrep%';
+----------------------------------+-------------------------------------------------------+
| Variable_name                    | Value                                                 |
+----------------------------------+-------------------------------------------------------+
| wsrep_local_state_uuid           | 23e153df-b664-11e9-89e3-ff2ae4f77a67                  |
| wsrep_protocol_version           | 9                                                     |
| wsrep_last_applied               | 16                                                    |
| wsrep_last_committed             | 16                                                    |
| wsrep_replicated                 | 1                                                     |
| wsrep_replicated_bytes           | 296                                                   |
| wsrep_repl_keys                  | 3                                                     |
| wsrep_repl_keys_bytes            | 48                                                    |
| wsrep_repl_data_bytes            | 178                                                   |
| wsrep_repl_other_bytes           | 0                                                     |
| wsrep_received                   | 6                                                     |
| wsrep_received_bytes             | 1206                                                  |
| wsrep_local_commits              | 1                                                     |
| wsrep_local_cert_failures        | 0                                                     |
| wsrep_local_replays              | 0                                                     |
| wsrep_local_send_queue           | 0                                                     |
| wsrep_local_send_queue_max       | 1                                                     |
| wsrep_local_send_queue_min       | 0                                                     |
| wsrep_local_send_queue_avg       | 0.000000                                              |
| wsrep_local_recv_queue           | 0                                                     |
| wsrep_local_recv_queue_max       | 1                                                     |
| wsrep_local_recv_queue_min       | 0                                                     |
| wsrep_local_recv_queue_avg       | 0.000000                                              |
| wsrep_local_cached_downto        | 14                                                    |
| wsrep_flow_control_paused_ns     | 0                                                     |
| wsrep_flow_control_paused        | 0.000000                                              |
| wsrep_flow_control_sent          | 0                                                     |
| wsrep_flow_control_recv          | 0                                                     |
| wsrep_flow_control_interval      | [ 173, 173 ]                                          |
| wsrep_flow_control_interval_low  | 173                                                   |
| wsrep_flow_control_interval_high | 173                                                   |
| wsrep_flow_control_status        | OFF                                                   |
| wsrep_cert_deps_distance         | 2.000000                                              |
| wsrep_apply_oooe                 | 0.000000                                              |
| wsrep_apply_oool                 | 0.000000                                              |
| wsrep_apply_window               | 1.000000                                              |
| wsrep_commit_oooe                | 0.000000                                              |
| wsrep_commit_oool                | 0.000000                                              |
| wsrep_commit_window              | 1.000000                                              |
| wsrep_local_state                | 4                                                     |
| wsrep_local_state_comment        | Synced                                                |
| wsrep_cert_index_size            | 5                                                     |
| wsrep_cert_bucket_count          | 22                                                    |
| wsrep_gcache_pool_size           | 2328                                                  |
| wsrep_causal_reads               | 0                                                     |
| wsrep_cert_interval              | 0.000000                                              |
| wsrep_open_transactions          | 0                                                     |
| wsrep_open_connections           | 0                                                     |
| wsrep_ist_receive_status         |                                                       |
| wsrep_ist_receive_seqno_start    | 0                                                     |
| wsrep_ist_receive_seqno_current  | 0                                                     |
| wsrep_ist_receive_seqno_end      | 0                                                     |
| wsrep_incoming_addresses         | 196.55.3.102:3308,196.55.3.102:3307,196.55.3.102:3306 |
| wsrep_cluster_weight             | 3                                                     |
| wsrep_desync_count               | 0                                                     |
| wsrep_evs_delayed                |                                                       |
| wsrep_evs_evict_list             |                                                       |
| wsrep_evs_repl_latency           | 0/0/0/0/0                                             |
| wsrep_evs_state                  | OPERATIONAL                                           |
| wsrep_gcomm_uuid                 | e0b9cedd-b698-11e9-90d1-8fe12b369d0b                  |
| wsrep_cluster_conf_id            | 3                                                     |
| wsrep_cluster_size               | 3                                                     |
| wsrep_cluster_state_uuid         | 23e153df-b664-11e9-89e3-ff2ae4f77a67                  |
| wsrep_cluster_status             | Primary                                               |
| wsrep_connected                  | ON                                                    |
| wsrep_local_bf_aborts            | 0                                                     |
| wsrep_local_index                | 2                                                     |
| wsrep_provider_name              | Galera                                                |
| wsrep_provider_vendor            | Codership Oy <info@codership.com>                     |
| wsrep_provider_version           | 3.37(r)                                               |
| wsrep_ready                      | ON                                                    |
+----------------------------------+-------------------------------------------------------+
71 rows in set (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| roidba             |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

mysql> set wsrep_on=off;
Query OK, 0 rows affected (0.00 sec)

mysql> use roidba
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+------------------+
| Tables_in_roidba |
+------------------+
| t                |
| t1               |
+------------------+
2 rows in set (0.00 sec)

mysql> drop table t;
Query OK, 0 rows affected (0.01 sec)

mysql> 
mysql> show tables;
+------------------+
| Tables_in_roidba |
+------------------+
| t1               |
+------------------+
1 row in set (0.00 sec)

pxc02-->node2

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| roidba             |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

mysql> use roidba;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+------------------+
| Tables_in_roidba |
+------------------+
| t                |
| t1               |
+------------------+
2 rows in set (0.00 sec)