Performance Schema Connection Attribute Tables 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” . The client user name for the connection. This is  NULL  for an internal thread, or for a user session that failed to authenticate. The current number of connections for the user. The total number of connections for the user. The  users  table has these indexes: 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: 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. 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. Available Connection Atrributes 27.12.9 Performance Schema Connection Attribute Tables • USER • CURRENT_CONNECTIONS • TOTAL_CONNECTIONS •Primary key on ( USER ) • 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 •Available Connection Atrributes •Connection Atrribute Limits 4992