Mariadb Galera Cluster Multi-Master 查询执行速度慢答案

【问题标题】：Mariadb Galera Cluster Multi-Master Slow execution of queriesMariadb Galera Cluster Multi-Master 查询执行速度慢
【发布时间】：2018-12-18 20:49:51
【问题描述】：

我对 Galera 多主机有疑问。当我在 node1 中运行 query(SELECT) 时执行 0.025 sec ，但在 node2 上执行相同的查询 5.172 sec 并且在 node3 中结果是 4.347强>秒。

Node1 配置：

[mysqld]

log_error=/var/log/mariadb.log

[galera]

wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.2.47,192.168.2.48,192.168.2.49,172.29.44.11"
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
wsrep_cluster_name="CCCluster"
bind-address=0.0.0.0
wsrep_node_address="192.168.2.47"
wsrep_node_name=”node1"
wsrep_sst_method=rsync

Node2 配置：

[mysqld]

log_error=/var/log/mariadb.log

[galera]

wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.2.47,192.168.2.48,192.168.2.49,172.29.44.11"
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
wsrep_cluster_name="CCCluster"
bind-address=0.0.0.0
wsrep_node_address="192.168.2.48"
wsrep_node_name="node2"
wsrep_sst_method=rsync

Node3 配置：

[mysqld]

log_error=/var/log/mariadb.log

[galera]

wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.2.47,192.168.2.48,192.168.2.49,172.29.44.11"
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
wsrep_cluster_name="CCCluster"
bind-address=0.0.0.0
wsrep_node_address="192.168.2.49"
wsrep_node_name="node1"
wsrep_sst_method=rsync

我在节点上执行的查询是：

select  `users`.*, `upd`.`first_name`, `upd`.`middle_name`, `upd`.`last_name`,
        CONCAT_WS(upd.first_name, upd.middle_name, upd.last_name) AS full_name
    from  `users`
    inner join  `users_personal_data` as `upd`  ON `upd`.`user_id` = `users`.`id`
    order by  `id` desc
    limit  20 offset 0;

这个问题从何而来？

【问题讨论】：

请在慢速节点之一上获取EXPLAIN SELECT ...。它可能会给我们一个线索。还有SHOW CREATE TABLE.

标签： mariadb galera multi-master-replication

【解决方案1】：

EXPLAIN SELECT 的结果是：

+------+-------------+-------+------+-------------------------------------+------+---------+------+------+-------------------------------------------------+
| id   | select_type | table | type | possible_keys                       | key  | key_len | ref  | rows | Extra                                           |
+------+-------------+-------+------+-------------------------------------+------+---------+------+------+-------------------------------------------------+
|    1 | SIMPLE      | users | ALL  | PRIMARY                             | NULL | NULL    | NULL |    1 | Using temporary; Using filesort                 |
|    1 | SIMPLE      | upd   | ALL  | users_personal_data_user_id_foreign | NULL | NULL    | NULL |    1 | Using where; Using join buffer (flat, BNL join) |
+------+-------------+-------+------+-------------------------------------+------+---------+------+------+-------------------------------------------------+

【讨论】：