content_image/699814.jpg content_image/699813.jpg content_image/699812.jpg
The variable value is a list of one or more comma-separated compression algorithm names, in any order, chosen from the following items (not case-sensitive): 

• zlib : Permit connections that use the zlib  compression algorithm. 

• zstd : Permit connections that use the zstd  compression algorithm (zstd 1.3). 

• uncompressed : Permit uncompressed connections. If this algorithm name is not included in the protocol_compression_algorithms  value, the server does not permit uncompressed connections. It permits only compressed connections that use whichever other algorithms are specified in the value, and there is no fallback to uncompressed connections. 

The default value of zlib,zstd,uncompressed  indicates that the server permits all compression algorithms. 

For more information, see Section 4.2.8, “Connection Compression Control” . 

• protocol_version 

<img src='content_image/699814.jpg'>

The version of the client/server protocol used by the MySQL server. 

• proxy_user 

<img src='content_image/699813.jpg'>

If the current client is a proxy for another user, this variable is the proxy user account name. Otherwise, this variable is NULL . See Section 6.2.18, “Proxy Users” . 

• pseudo_slave_mode 

<img src='content_image/699812.jpg'>

