X Plugin Options and Variables •If a client requests an algorithm compression level that is less than the server minimum permitted level, the server uses the minimum permitted level. Monitoring Connection Compression for X Plugin You can monitor the effects of message compression using the X Plugin status variables. When message compression is in use, the session  Mysqlx_compression_algorithm  status variable shows which compression algorithm is in use for the current X Protocol connection, and Mysqlx_compression_level  shows the compression level that was selected. These session status variables are available from MySQL 8.0.20. From MySQL 8.0.19, X Plugin status variables can be used to calculate the efficiency of the compression algorithms that are selected (the data compression ratio), and the overall effect of using message compression. Use the session value of the status variables in the following calculations to see what the benefit of message compression was for a specific session with a known compression algorithm. Or use the global value of the status variables to check the overall benefit of message compression for your server across all sessions using X Protocol connections, including all the compression algorithms that have been used for those sessions, and all sessions that did not use message compression. You can then tune message compression by adjusting the permitted compression algorithms, maximum compression level, and default compression level, as described in Configuring Connection Compression for X Plugin. When message compression is in use, the  Mysqlx_bytes_sent  status variable shows the total number of bytes sent out from the server, including compressed message payloads measured after compression, any items in compressed messages that were not compressed such as X Protocol headers, and any uncompressed messages. The  Mysqlx_bytes_sent_compressed_payload  status variable shows the total number of bytes sent as compressed message payloads, measured after compression, and the Mysqlx_bytes_sent_uncompressed_frame  status variable shows the total number of bytes for those same message payloads but measured before compression. The compression ratio, which shows the efficiency of the compression algorithm, can therefore be calculated using the following expression: The effectiveness of compression for X Protocol messages sent by the server can be calculated using the following expression: For messages received by the server from clients, the Mysqlx_bytes_received_compressed_payload  status variable shows the total number of bytes received as compressed message payloads, measured before decompression, and the Mysqlx_bytes_received_uncompressed_frame  status variable shows the total number of bytes for those same message payloads but measured after decompression. The  Mysqlx_bytes_received status variable includes compressed message payloads measured before decompression, any uncompressed items in compressed messages, and any uncompressed messages. This section describes the command options and system variables that configure X Plugin, as well as the status variables available for monitoring purposes. If configuration values specified at startup time are incorrect, X Plugin could fail to initialize properly and the server does not load it. In this case, the server could also produce error messages for other X Plugin settings because it cannot recognize them. This table provides an overview of the command options, system variables, and status variables provided by X Plugin. 3891 20.5.6 X Plugin Options and Variables 20.5.6.1 X Plugin Option and Variable Reference mysqlx_bytes_sent_uncompressed_frame / mysqlx_bytes_sent_compressed_payload (mysqlx_bytes_sent