[MDEV-11123] `Seconds_Behind_Master` is not accessible through `information_schema` Created: 2016-10-24  Updated: 2019-03-18

Status: Open
Project: MariaDB Server
Component/s: Replication
Affects Version/s: 10.1.18
Fix Version/s: 10.2

Type: Bug Priority: Minor
Reporter: Christian Rishøj Assignee: Andrei Elkin
Resolution: Unresolved Votes: 0
Labels: show_slave_status
Environment:

Ubuntu Linux


 Description   

Seconds_Behind_Master (and possibly other replication-related status variables) are not accessible through INFORMATION_SCHEMA.GLOBAL_STATUS:

MariaDB [information_schema]> SELECT * FROM GLOBAL_STATUS WHERE VARIABLE_NAME LIKE '%seconds%';
 
Empty set (0.00 sec)

This seems inconsistent, since other replication-related status variables are accessible:

MariaDB [information_schema]> SELECT * FROM GLOBAL_STATUS WHERE VARIABLE_NAME LIKE 'slave%';
 
+----------------------------+----------------+
 
| VARIABLE_NAME              | VARIABLE_VALUE |
 
+----------------------------+----------------+
 
| SLAVE_CONNECTIONS          | 15             |
 
| SLAVE_HEARTBEAT_PERIOD     | 30.000         |
 
| SLAVE_OPEN_TEMP_TABLES     | 0              |
 
| SLAVE_RECEIVED_HEARTBEATS  | 505            |
 
| SLAVE_RETRIED_TRANSACTIONS | 0              |
 
| SLAVE_RUNNING              | ON             |
 
| SLAVE_SKIPPED_ERRORS       | 0              |
 
| SLAVES_CONNECTED           | 1              |
 
| SLAVES_RUNNING             | 1              |
 
+----------------------------+----------------+
 
9 rows in set (0.00 sec)

A possible use case could be defining EVENTs to create a self-contained monitoring solution for replication lag in a multi-master environment. Currently, the only way to get Seconds_Behind_Master from SQL is to use a CURSOR to parse the output of SHOW SLAVE STATUS in a procedure...
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