MySQL 9.3 Reference Manual Including MySQL NDB Cluster 9.3
To monitor the status of replication channels the following options exist:
Using the replication Performance Schema tables. The first
column of these tables is Channel_Name.
This enables you to write complex queries based on
Channel_Name as a key. See
Section 29.12.11, “Performance Schema Replication Tables”.
Using SHOW REPLICA
STATUS FOR CHANNEL
. By default, if
the channelFOR CHANNEL
clause is not
used, this statement shows the replica status for all channels
with one row per channel. The identifier
channelChannel_name is added as a column in the
result set. If a FOR CHANNEL
clause is
provided, the results show the status of only the named
replication channel.
channel
The SHOW VARIABLES statement does
not work with multiple replication channels. The information
that was available through these variables has been migrated to
the replication performance tables. Using a
SHOW VARIABLES statement in a
topology with multiple channels shows the status of only the
default channel.
The error codes and messages that are issued when multi-source replication is enabled specify the channel that generated the error.
This section explains how to use the replication Performance Schema tables to monitor channels. You can choose to monitor all channels, or a subset of the existing channels.
To monitor the connection status of all channels:
mysql> SELECT * FROM replication_connection_status\G;
*************************** 1. row ***************************
CHANNEL_NAME: source_1
GROUP_NAME:
SOURCE_UUID: 046e41f8-a223-11e4-a975-0811960cc264
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
*************************** 2. row ***************************
CHANNEL_NAME: source_2
GROUP_NAME:
SOURCE_UUID: 7475e474-a223-11e4-a978-0811960cc264
THREAD_ID: 26
SERVICE_STATE: ON
COUNT_RECEIVED_HEARTBEATS: 0
LAST_HEARTBEAT_TIMESTAMP: 0000-00-00 00:00:00
RECEIVED_TRANSACTION_SET: 7475e474-a223-11e4-a978-0811960cc264:4-6
LAST_ERROR_NUMBER: 0
LAST_ERROR_MESSAGE:
LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00
2 rows in set (0.00 sec)
In the above output there are two channels enabled, and as shown
by the CHANNEL_NAME field they are called
source_1 and source_2.
The addition of the CHANNEL_NAME field
enables you to query the Performance Schema tables for a
specific channel. To monitor the connection status of a named
channel, use a WHERE
CHANNEL_NAME=
clause:
channel
mysql> SELECT * FROM replication_connection_status WHERE CHANNEL_NAME='source_1'\G
*************************** 1. row ***************************
CHANNEL_NAME: source_1
GROUP_NAME:
SOURCE_UUID: 046e41f8-a223-11e4-a975-0811960cc264
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= clause
can be used to monitor the other replication Performance Schema
tables for a specific channel. For more information, see
Section 29.12.11, “Performance Schema Replication Tables”.
channel