You can monitor the effects of binary log transaction compression using the Performance Schema table binary_log_transaction_compression_stats. The statistics include the data compression ratio for the monitored period, and you can also view the effect of compression on the last transaction on the server. You can reset the statistics by truncating the table. Statistics for binary logs and relay logs are split out so you can see the impact of compression for each log type. The MySQL server instance must have a binary log to produce these statistics.

The Performance Schema table events_stages_current shows when a transaction is in the stage of decompression or compression for its transaction payload, and displays its progress for this stage. Compression is carried out by the worker thread handling the transaction, just before the transaction is committed, provided that there are no events in the finalized capture cache that exclude the transaction from binary log transaction compression (for example, incident events). When decompression is required, it is carried out for one event from the payload at a time.

mysqlbinlog with the --verbose option includes comments stating the compressed size and the uncompressed size for compressed transaction payloads, and the compression algorithm that was used.

You can enable connection compression at the protocol level for replication connections, using the SOURCE_COMPRESSION_ALGORITHMS | MASTER_COMPRESSION_ALGORITHMS and SOURCE_ZSTD_COMPRESSION_LEVEL | MASTER_ZSTD_COMPRESSION_LEVELoptions of the CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23), or the deprecated slave_compressed_protocol system variable. If you enable binary log transaction compression in a system where connection compression is also enabled, the impact of connection compression is reduced, as there might be little opportunity to further compress the compressed transaction payloads. However, connection compression can still operate on uncompressed events and on message headers. Binary log transaction compression can be enabled in combination with connection compression if you need to save storage space as well as network bandwidth. For more information on connection compression for replication connections, see Section 4.2.8, “Connection Compression Control”.

For Group Replication, compression is enabled by default for messages that exceed the threshold set by the group_replication_compression_threshold system variable. You can also configure compression for messages sent for distributed recovery by the method of state transfer from a donor's binary log, using the group_replication_recovery_compression_algorithms and group_replication_recovery_zstd_compression_level system variables. If you enable binary log transaction compression in a system where these are configured, Group Replication's message compression can still operate on uncompressed events and on message headers, but its impact is reduced. For more information on message compression for Group Replication, see Section 18.7.3, “Message Compression”.