Reading table information for completion of table and column names

This problem is found when the command line operates the database:

mysql> Use dbname Reading table information for completion of table and column names
You can turn off the feature to get a quicker startup with-a

And then it's stuck here.

is because the database is too large, that is, the table in the database is very much, so if you read the database information, will be very slow, so it jammed, if the table in the database is very small, there will be no problem.

The problem occurs because:
When we entered MySQL, the-a parameter was not used;
that we use
Mysql-hhostname-uusername-ppassword-pport the way into the data,
And not using
Mysql-hhostname-uusername-ppassword-pport-a the way into the database.

       When we open the database, that is,   use dbname, we want to read the database information, and when the-a parameter is used, the database information is not read.