MaxScale：无法检索数据库名称

Question

当我开始maxscale，我得到以下错误：

... 
2017-01-17 20:26:05 debug : qc_sqlite: Token 34 not handled explicitly. 
2017-01-17 20:26:05 debug : qc_sqlite: Token 103 not handled explicitly. 
2017-01-17 20:26:05 debug : qc_sqlite: Token 216 not handled explicitly. 
2017-01-17 20:26:05 notice : Loaded module maxscaled: V2.0.0 from /usr/lib64/maxscale/libmaxscaled.so 
2017-01-17 20:26:05 notice : Listening connections at /tmp/maxadmin.sock with protocol MaxScale Admin 
2017-01-17 20:26:05 debug : 140414757828672 [poll_add_dcb] Added dcb 0x1ad27f0 in state DCB_STATE_LISTENING to poll set. 
2017-01-17 20:26:05 notice : Using encrypted passwords. Encryption key: '/var/lib/maxscale/.secrets'. 
2017-01-17 20:26:05 error : Failed to retrieve database names: 
2017-01-17 20:26:05 error : Shard Router: Unable to load database grant information, MaxScale authentication will proceed without including database permissions. See earlier error messages for user '*******' for more information. 
2017-01-17 20:26:05 error : Failed to retrieve database names: 
2017-01-17 20:26:05 error : Shard Router: Unable to load database grant information, MaxScale authentication will proceed without including database permissions. See earlier error messages for user '*******' for more information. 

我启用调试，并且仍然无法看到“前面”的消息是什么！ 我可以使用配置的帐户连接到服务器，并且我没有任何问题地运行show数据库。

数据库位于RDS中。

有什么想法？

感谢

Answer 1

它没有问题，该maxscale能够运行“显示数据库”，它需要显示数据库的明确授予，因为它运行：

SELECT * 
FROM ( 
    ( 
      SELECT Count(1) AS ndbs 
      FROM information_schema.schemata) AS tbl1, 
    ( 
      SELECT grantee, 
       privilege_type 
      FROM information_schema.user_privileges 
      WHERE privilege_type='SHOW DATABASES' 
      AND REPLACE(grantee, '\'','')=CURRENT_USER()) AS tbl2); 

所以，没有特别授予该priv，查询将不会返回任何内容。

Answer 2

MaxScale用户的授权要求在MaxScale Tutorial中描述。

为maxuser@%用户所需的补助是：

GRANT SELECT ON mysql.user TO 'maxuser'@'%'; 
GRANT SELECT ON mysql.db TO 'maxuser'@'%'; 
GRANT SELECT ON mysql.tables_priv TO 'maxuser'@'%'; 
GRANT SHOW DATABASES ON *.* TO 'maxuser'@'%'; 
GRANT REPLICATION CLIENT ON *.* TO 'maxuser'@'%';