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THREAD_ID: 24 SERVICE_STATE: ON COUNT_RECEIVED_HEARTBEATS: 0 LAST_HEARTBEAT_TIMESTAMP: 0000-00-00 00:00:00 RECEIVED_TRANSACTION_SET: 046e41f8-a223-11e4-a975-0811960cc264:4-37 LAST_ERROR_NUMBER: 0 LAST_ERROR_MESSAGE: LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 1 row in set (0.00 sec) 

Similarly, the WHERE CHANNEL_NAME= channel  clause can be used to monitor the other replication Performance Schema tables for a specific channel. For more information, see Section 27.12.11, “Performance Schema Replication Tables” . 

## 17.1.6 Replication and Binary Logging Options and Variables 

The following sections contain information about mysqld  options and server variables that are used in replication and for controlling the binary log. Options and variables for use on sources and replicas are covered separately, as are options and variables relating to binary logging and global transaction identifiers (GTIDs). A set of quick-reference tables providing basic information about these options and variables is also included. 

Of particular importance is the server_id  system variable. 

<img src='content_image/810352.jpg'>

This variable specifies the server ID. server_id  is set to 1 by default. The server can be started with this default ID, but when binary logging is enabled, an informational message is issued if you did not set server_id  explicitly to specify a server ID. 

For servers that are used in a replication topology, you must specify a unique server ID for each replication server, in the range from 1 to 2$^{32}$ − 1. “Unique”  means that each ID must be different from every other ID in use by any other source or replica in the replication topology. For additional information, see Section 17.1.6.2, “Replication Source Options and Variables” , and Section 17.1.6.3, “Replica Server Options and Variables” . 

If the server ID is set to 0, binary logging takes place, but a source with a server ID of 0 refuses any connections from replicas, and a replica with a server ID of 0 refuses to connect to a source. Note that although you can change the server ID dynamically to a nonzero value, doing so does not enable replication to start immediately. You must change the server ID and then restart the server to initialize the replica. 

For more information, see Section 17.1.2.2, “Setting the Replica Configuration” . 

server_uuid 

