Description:
https://dev.mysql.com/doc/refman/8.0/en/connection-compression-control.html says：
1.
If the replica_compressed_protocol or slave_compressed_protocol system variable is enabled, it takes precedence over MASTER_COMPRESSION_ALGORITHMS and connections to the source use zlib compression if both source and replica permit that algorithm. If replica_compressed_protocol or slave_compressed_protocol is disabled, the value of MASTER_COMPRESSION_ALGORITHMS applies.
2.
For source/replica replication connections, the configured compression algorithms and compression level are available from multiple sources:
The Performance Schema replication_connection_configuration table has COMPRESSION_ALGORITHMS and ZSTD_COMPRESSION_LEVEL columns.
The mysql.slave_master_info system table has Master_compression_algorithms and Master_zstd_compression_level columns. If the master.info file exists, it contains lines for those values as well.
now I set slave_compressed_protocol=on on both master and slave side, and execute stop slave;start slave;
Then the connection between master and slave should be compressed.
select * from slave_master_info \G
*************************** 1. row ***************************
Number_of_lines: 32
Master_log_name: binlog.000049
Master_log_pos: 31704724
Host: 172.21.16.12
User_name: tdsqlsys_repl
User_password: G1LCYqO6b%qUHxUM0q
Port: 4008
Connect_retry: 60
Enabled_ssl: 0
Ssl_ca:
Ssl_capath:
Ssl_cert:
Ssl_cipher:
Ssl_key:
Ssl_verify_server_cert: 0
Heartbeat: 1800
Bind:
Ignored_server_ids: 0
Uuid: 9f800d30-bf16-11ee-a37b-525400eb8e01
Retry_count: 86400
Ssl_crl:
Ssl_crlpath:
Enabled_auto_position: 1
Channel_name:
Tls_version:
Public_key_path:
Get_public_key: 0
Network_namespace:
Master_compression_algorithm: uncompressed
Master_zstd_compression_level: 3
Tls_ciphersuites: NULL
Source_connection_auto_failover: 0
select * from performance_schema.replication_connection_configuration \G
*************************** 1. row ***************************
CHANNEL_NAME:
HOST: 172.21.16.12
PORT: 4008
USER: tdsqlsys_repl
NETWORK_INTERFACE:
AUTO_POSITION: 1
SSL_ALLOWED: NO
SSL_CA_FILE:
SSL_CA_PATH:
SSL_CERTIFICATE:
SSL_CIPHER:
SSL_KEY:
SSL_VERIFY_SERVER_CERTIFICATE: NO
SSL_CRL_FILE:
SSL_CRL_PATH:
CONNECTION_RETRY_INTERVAL: 60
CONNECTION_RETRY_COUNT: 86400
HEARTBEAT_INTERVAL: 1800.000
TLS_VERSION:
PUBLIC_KEY_PATH:
GET_PUBLIC_KEY: NO
NETWORK_NAMESPACE:
COMPRESSION_ALGORITHM: uncompressed
ZSTD_COMPRESSION_LEVEL: 3
TLS_CIPHERSUITES: NULL
SOURCE_CONNECTION_AUTO_FAILOVER: 0
it seems that performance_schema.replication_connection_configuration gets the data from slave_master_info.
the COMPRESSION_ALGORITHM still display uncompressed.
I think it should be output zlib.
How to repeat:
see above
