Server System Variables variable is enabled; otherwise, or for roles that are set as default roles otherwise. At runtime,  SET ROLE activates roles. Roles that do not exist when assigned to  mandatory_roles  but are created later may require special treatment to be considered mandatory. For details, see Defining Mandatory Roles. SHOW GRANTS  displays mandatory roles according to the rules described in Section 13.7.7.21, “SHOW GRANTS Statement” . The maximum size of one packet or any generated/intermediate string, or any parameter sent by the mysql_stmt_send_long_data() C API function. The default is 64MB. The packet message buffer is initialized to  net_buffer_length  bytes, but can grow up to max_allowed_packet  bytes when needed. This value by default is small, to catch large (possibly incorrect) packets. You must increase this value if you are using large  BLOB  columns or long strings. It should be as big as the largest  BLOB  you want to use. The protocol limit for  max_allowed_packet  is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple. When you change the message buffer size by changing the value of the  max_allowed_packet variable, you should also change the buffer size on the client side if your client program permits it. The default  max_allowed_packet  value built in to the client library is 1GB, but individual client programs might override this. For example,  mysql  and  mysqldump  have defaults of 16MB and 24MB, respectively. They also enable you to change the client-side value by setting  max_allowed_packet  on the command line or in an option file. The session value of this variable is read only. The client can receive up to as many bytes as the session value. However, the server does not send to the client more bytes than the current global max_allowed_packet  value. (The global value could be less than the session value if the global value is changed after the client connects.) • max_allowed_packet • max_connect_errors 828 Command-Line Format --max-allowed-packet=# System Variable max_allowed_packet Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 67108864 Minimum Value 1024 Maximum Value 1073741824 Block Size 1024 Command-Line Format --max-connect-errors=# System Variable max_connect_errors Scope Global