Replication and Binary Logging Options and Variables Maximum Value 4294967295 Unit milliseconds Sets the maximum time (in milliseconds) that is allowed to pass before a checkpoint operation is called to update the status of a multithreaded replica as shown by  SHOW REPLICA | SLAVE STATUS . Setting this variable has no effect on replicas for which multithreading is not enabled. Setting this variable takes effect for all replication channels immediately, including running channels. Multithreaded replicas are not currently supported by NDB Cluster, which silently ignores the setting for this variable. See Section 23.6.3, “Known Issues in NDB Cluster Replication” , for more information. This variable works in combination with the  slave_checkpoint_group  system variable in such a way that, when either limit is exceeded, the checkpoint is executed and the counters tracking both the number of transactions and the time elapsed since the last checkpoint are reset. The minimum allowed value for this variable is 1, unless the server was built using  -DWITH_DEBUG , in which case the minimum value is 0. Regardless of how the server was built, the default value is 300, and the maximum possible value is 4294967295 (4GB). Whether to use compression of the source/replica connection protocol if both source and replica support it. If this variable is disabled (the default), connections are uncompressed. Changes to this variable take effect on subsequent connection attempts; this includes after issuing a  START REPLICA | SLAVE statement, as well as reconnections made by a running replication I/O thread. Binary log transaction compression (available as of MySQL 8.0.20), which is activated by the binlog_transaction_compression  system variable, can also be used to save bandwidth. If you use binary log transaction compression in combination with protocol compression, protocol compression has less opportunity to act on the data, but can still compress headers and those events and transaction payloads that are uncompressed. For more information on binary log transaction compression, see Section 5.4.4.5, “Binary Log Transaction Compression” . As of MySQL 8.0.18, if  slave_compressed_protocol  is enabled, it takes precedence over any SOURCE_COMPRESSION_ALGORITHMS  |  MASTER_COMPRESSION_ALGORITHMS  option specified for the  CHANGE REPLICATION SOURCE TO  |  CHANGE MASTER TO  statement. In this case, connections to the source use  zlib  compression if both the source and replica support that algorithm. If  slave_compressed_protocol  is disabled, the value of  SOURCE_COMPRESSION_ALGORITHMS  | 3529 • slave_compressed_protocol Command-Line Format --slave-compressed-protocol[={OFF| ON}] Deprecated 8.0.18 System Variable slave_compressed_protocol Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Boolean Default Value OFF Note