optimize table mysql.user;
Table	Op	Msg_type	Msg_text
mysql.user	optimize	status	OK
insert mysql.user (user,plugin) values ('foo','bar'),('bar','bar'),('baz','bar');
Warnings:
Warning	1364	Field 'ssl_cipher' doesn't have a default value
Warning	1364	Field 'x509_issuer' doesn't have a default value
Warning	1364	Field 'x509_subject' doesn't have a default value
Warning	1364	Field 'authentication_string' doesn't have a default value
flush privileges;
connect(localhost,u1,,test,MASTER_PORT,MASTER_SOCKET);
ERROR HY000: Plugin 'bar' is not loaded
connect(localhost,u2,,test,MASTER_PORT,MASTER_SOCKET);
ERROR 28000: Access denied for user 'u2'@'localhost' (using password: NO)
connect(localhost,u2,password,test,MASTER_PORT,MASTER_SOCKET);
ERROR 28000: Access denied for user 'u2'@'localhost' (using password: YES)
ERROR HY000: Plugin 'bar' is not loaded
ERROR 28000: Access denied for user 'u2'@'localhost' (using password: NO)
ERROR 28000: Access denied for user 'u2'@'localhost' (using password: YES)
delete from mysql.user where plugin = 'bar';
flush privileges;