Description:
Under Recovery Condition, Received_transaction_set and GTID_EXECUTED became upside down.
Under normal condition, everything working fine.
-------------------------------------
Please confirm following example
-------------------------------------
localhost [(none)]> SELECT * FROM performance_schema.replication_group_members;SELECT member_host as "primary master" FROM performance_schema.global_status JOIN performance_schema.replication_group_members WHERE variable_name = 'group_replication_primary_member' AND member_id=variable_value;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 42c3cbdc-d216-14h9-b56c-02011477005e | TST-db-12 | 3306 | ONLINE |
| group_replication_applier | e1731e29-d216-14h9-8646-020114770060 | TST-db-14 | 3306 | RECOVERING |
| group_replication_applier | e53e17a3-d216-14h9-98c5-02011477005f | TST-db-13 | 3306 | ONLINE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
3 rows in set (0.00 sec)
+----------------+
| primary master |
+----------------+
| TST-db-12 |
+----------------+
1 row in set (0.00 sec)
It seems "Received_transaction_set" is not showing latest status.
It is under "@@global.GTID_EXECUTED".
localhost [performance_schema]> select Received_transaction_set FROM performance_schema.replication_connection_status WHERE Channel_name = 'group_replication_applier'; select @@global.GTID_EXECUTED;
+--------------------------------------------------------------------------------------------+
| Received_transaction_set |
+--------------------------------------------------------------------------------------------+
| cb904887-a1fc-11e8-ae58-02011477005e:1-24598537 |
+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
+--------------------------------------------------------------------------------------------+
| @@global.GTID_EXECUTED |
+--------------------------------------------------------------------------------------------+
| cb904887-a1fc-11e8-ae58-02011477005e:1-24598559 |
+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
localhost [performance_schema]> select @last_exec:=SUBSTRING_INDEX(SUBSTRING_INDEX(SUBSTRING_INDEX( @@global.GTID_EXECUTED,':',-1),':',1),'-',-1) last_executed;select @last_rec:=SUBSTRING_INDEX(SUBSTRING_INDEX(SUBSTRING_INDEX( Received_transaction_set,':',-1),':',1),'-',-1) last_received FROM performance_schema.replication_connection_status WHERE Channel_name = 'group_replication_applier';select (@last_rec - @last_exec) as real_lag;
+---------------+
| last_executed |
+---------------+
| 24598559 |
+---------------+
1 row in set (0.00 sec)
+---------------+
| last_received |
+---------------+
| 24598537 |
+---------------+
1 row in set (0.00 sec)
+----------+
| real_lag |
+----------+
| -22 | ← "In this case under -22"
+----------+
1 row in set (0.00 sec)
How to repeat:
1) STOP ONE OF INSTANCE UNDER GROUP REPLICATION.
2) RUN Large Volume of Transaction. (Such as delete large table)
3) START STOPPED INSTANCE.
4) THE INSTANCE BECAME RECOVERING MODE
5) Please check the lag between Received_transaction_set and @@global.GTID_EXECUTED.
Suggested fix:
Received_transaction_set should be under @@global.GTID_EXECUTED.
