> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/clientserver-protocol/replication-protocol.md).

# Replication Protocol

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[1-Binlog Events](/docs/server/reference/clientserver-protocol/replication-protocol/1-binlog-events.md)
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This section provides an overview of the various events recorded in the binary log, which are the core units of replication data transmission.
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[2-Binlog Event Header](/docs/server/reference/clientserver-protocol/replication-protocol/2-binlog-event-header.md)
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Every binary log event starts with a standardized header containing metadata such as the timestamp, event type, server ID, and event size.
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[3-Binlog Network Stream](/docs/server/reference/clientserver-protocol/replication-protocol/3-binlog-network-stream.md)
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Describes the continuous packet stream format used to transmit binary log events from the primary server to the replica over the network.
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{% content-ref url="/pages/9UPEIfhZ4L8oBFbEFKfg" %}
[4-Semi-Sync Replication](/docs/server/reference/clientserver-protocol/replication-protocol/4-semi-sync-replication.md)
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Explains the handshake and acknowledgement process for semi-synchronous replication, ensuring data is committed on at least one replica.
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{% content-ref url="/pages/nnsqmhxQhp6NBNw9DYBG" %}
[5-Replica Registration](/docs/server/reference/clientserver-protocol/replication-protocol/5-replica-registration.md)
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Details the initialization phase where a replica connects to the primary, authenticates, sends capabilities, and registers for updates.
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{% content-ref url="/pages/u3d4b1wrbiAeVliD3TfX" %}
[ANNOTATE\_ROWS\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/annotate_rows_event.md)
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This event accompanies row-based events to provide the original SQL query text, which is useful for auditing and debugging replication.
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{% content-ref url="/pages/3dr29JjH3UTmxRHjSsBW" %}
[BEGIN\_LOAD\_QUERY\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/begin_load_query_event.md)
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Used during LOAD DATA INFILE operations, this event marks the beginning of the data load and contains the initial query information.
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{% content-ref url="/pages/HvKfFT2viXClLf2VlKc6" %}
[BINLOG\_CHECKPOINT\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/binlog_checkpoint_event.md)
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A marker event indicating a checkpoint in the binary log, used to ensure consistency and safe rotation of log files.
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[COM\_BINLOG\_DUMP](/docs/server/reference/clientserver-protocol/replication-protocol/com_binlog_dump.md)
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This command is sent by a replica to the primary server to request the start of the binary log event stream from a specific file and position.
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[COM\_REGISTER\_SLAVE](/docs/server/reference/clientserver-protocol/replication-protocol/com_register_slave.md)
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This command is used by a replica to register its details, such as server ID, hostname, and port, with the primary server.
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[EXECUTE\_LOAD\_QUERY\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/execute_load_query_event.md)
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This event is used for LOAD DATA INFILE operations, managing the execution phase similar to a QUERY\_EVENT but with extra static fields for file handling.
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[Fake GTID\_LIST Event](/docs/server/reference/clientserver-protocol/replication-protocol/fake-gtid_list-event.md)
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A synthetic event sent by the master after the initial handshake to inform the replica of its current GTID state, it is not written to the binary log.
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{% content-ref url="/pages/1UoW35tOHMNq7FI4COoa" %}
[Fake ROTATE\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/fake-rotate_event.md)
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An artificial event sent to the replica to indicate the name of the binary log file on the master, ensuring the replica knows which file is being read.
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[FORMAT\_DESCRIPTION\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/format_description_event.md)
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This descriptor event appears at the start of every binary log file, defining the server version, binlog version, and header lengths for all event types.
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[GTID\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/gtid_event.md)
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The GTID\_EVENT marks the start of a new transaction event group, associating it with a Global Transaction ID (GTID) and providing commit flags.
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[GTID\_LIST\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/gtid_list_event.md)
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Logged during binlog rotation or checkpoints, this event lists the GTIDs present in the binary log to help replicas determine their replication state.
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[HEARTBEAT\_LOG\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/heartbeat_log_event.md)
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A heartbeat event sent over the network by the master when there are no binlog events, ensuring the replica knows the connection is still active.
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[INTVAR\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/intvar_event.md)
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This event records integer values for auto-increment columns or the LAST\_INSERT\_ID function, ensuring that these values are replicated deterministically.
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[QUERY\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/query_event.md)
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The QUERY\_EVENT records text-based SQL statements for statement-based replication, capturing the query string and execution context like the default database.
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[RAND\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/rand_event.md)
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The RAND\_EVENT records the two seed values used for the random number generator, ensuring that calls to the RAND() function produce identical results on replicas.
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[ROTATE\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/rotate_event.md)
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The ROTATE\_EVENT indicates a log rotation, specifying the name of the next binary log file and the position where writing will continue.
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[ROWS\_EVENT\_V1/V2, ROWS\_COMPRESSED\_EVENT\_V1](/docs/server/reference/clientserver-protocol/replication-protocol/rows_event_v1v2-rows_compressed_event_v1.md)
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These events record row-level changes (WRITE, UPDATE, DELETE) for replication, with versions supporting different column counts and compression.
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[START\_ENCRYPTION\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/start_encryption_event.md)
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This event marks the beginning of encrypted data in the binary log, defining the encryption scheme and key version for subsequent events.
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[STOP\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/stop_event.md)
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The STOP\_EVENT is written to the binary log when the server shuts down, serving as a marker for a clean stop.
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[TABLE\_MAP\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/table_map_event.md)
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This event provides a mapping between a table ID and its table definition, preceding row events to interpret the row data correctly.
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[USER\_VAR\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/user_var_event.md)
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The USER\_VAR\_EVENT logs the value of a user-defined variable, ensuring that statements using variables replicate consistently.
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{% content-ref url="/pages/kmM4fu5NgS7DDC74JUcM" %}
[XA\_PREPARE\_LOG\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/xa_prepare_log_event.md)
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This event records the preparation phase of an XA transaction, storing the XID to support two-phase commit and recovery.
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[XID\_EVENT](/docs/server/reference/clientserver-protocol/replication-protocol/xid_event.md)
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The XID\_EVENT signifies the commit of a transaction, containing the transaction ID (XID) to ensure atomicity across replication.
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