The users  table contains a row for each user who has connected to the MySQL server. For each user name, the table counts the current and total number of connections. The table size is autosized at server startup. To set the table size explicitly, set the performance_schema_users_size  system variable at server startup. To disable user statistics, set this variable to 0. 

The users  table has the following columns. For a description of how the Performance Schema maintains rows in this table, including the effect of TRUNCATE TABLE , see Section 27.12.8, “Performance Schema Connection Tables” . 

• USER 

The client user name for the connection. This is NULL  for an internal thread, or for a user session that failed to authenticate. 

• CURRENT_CONNECTIONS 

The current number of connections for the user. 

• TOTAL_CONNECTIONS 

The total number of connections for the user. 

The users  table has these indexes: 

•Primary key on ( USER ) 

## 27.12.9 Performance Schema Connection Attribute Tables 

Connection attributes are key-value pairs that application programs can pass to the server at connect time. For applications based on the C API implemented by the libmysqlclient  client library, the mysql_options()  and mysql_options4()  functions define the connection attribute set. Other MySQL Connectors may provide their own attribute-definition methods. 

These Performance Schema tables expose attribute information: 

• session_account_connect_attrs : Connection attributes for the current session, and other sessions associated with the session account 

• session_connect_attrs : Connection attributes for all sessions 

In addition, connect events written to the audit log may include connection attributes. See Section 6.4.5.4, “Audit Log File Formats” . 

Attribute names that begin with an underscore ( _ ) are reserved for internal use and should not be created by application programs. This convention permits new attributes to be introduced by MySQL without colliding with application attributes, and enables application programs to define their own attributes that do not collide with internal attributes. 

## Available Connection Atrributes 

•Available Connection Atrributes 

•Connection Atrribute Limits 

The set of connection attributes visible within a given connection varies depending on factors such as your platform, MySQL Connector used to establish the connection, or client program. 

