Bug #93177 Un-existing replication system variables mentioned in documentation.
Submitted: 13 Nov 2018 21:16 Modified: 8 Jan 2019 4:40
Reporter: Jean-François Gagné Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.5, 5.6, 5.7, 8.0 OS:Any
Assigned to: CPU Architecture:Any

[13 Nov 2018 21:16] Jean-François Gagné
Description:
Hi,

In 5.5, 5.6, 5.7, 8.0 Replication and Binary Logging Option and Variable Reference documentations (respectively [1], [2], [3] and [4]), there is a mention about a Com_show_new_master "system variables" applicable to replication and the binary log.  However, I do not find this in 5.7.24 and 8.0.13 (see how to repeat for details).  Also, in 5.7 and 8.0 documentations, there is a reference to Com_show_slave_status_nonblocking that I am not able to find either.

[1]: https://dev.mysql.com/doc/refman/5.5/en/replication-options-reference.html

[2]: https://dev.mysql.com/doc/refman/5.6/en/replication-options-reference.html

[3]: https://dev.mysql.com/doc/refman/5.7/en/replication-options-reference.html

[4]: https://dev.mysql.com/doc/refman/8.0/en/replication-options-reference.html

It looks like SHOW NEW MASTER was removed in 5.5 (according to [5]).

[5]: https://dev.mysql.com/worklog/task/?id=5670

There is a mention of SHOW SLAVE STATUS NONBLOCKING in [6], but it looks like it "disappeared" between 5.7.7 and 5.7.24 and 8.0.13 (see how to repeat for details).

[6]: http://mysqlserverteam.com/whats-new-in-mysql-5-7-first-release-candidate/

Many thanks for fixing the documentation,

JFG

How to repeat:
master [localhost] {msandbox} ((none)) > show global variables like 'version'; show global status like '%master%'; show global status like '%slave%'; SHOW SLAVE STATUS; SHOW SLAVE STATUS NONBLOCKING;
+---------------+------------+
| Variable_name | Value      |
+---------------+------------+
| version       | 5.7.24-log |
+---------------+------------+
1 row in set (0.01 sec)

+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| Com_change_master      | 0     |
| Com_show_master_status | 0     |
+------------------------+-------+
2 rows in set (0.00 sec)

+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| Com_show_slave_hosts   | 0     |
| Com_show_slave_status  | 0     |
| Com_slave_start        | 0     |
| Com_slave_stop         | 0     |
| Slave_open_temp_tables | 0     |
+------------------------+-------+
5 rows in set (0.00 sec)

Empty set (0.00 sec)

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NONBLOCKING' at line 1

master [localhost] {msandbox} ((none)) > show global variables like 'version'; show global status like '%master%'; show global status like '%slave%'; SHOW SLAVE STATUS; SHOW SLAVE STATUS NONBLOCKING;
+---------------+--------+
| Variable_name | Value  |
+---------------+--------+
| version       | 8.0.13 |
+---------------+--------+
1 row in set (0.00 sec)

+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| Com_change_master      | 0     |
| Com_show_master_status | 0     |
+------------------------+-------+
2 rows in set (0.00 sec)

+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| Com_show_slave_hosts   | 0     |
| Com_show_slave_status  | 0     |
| Com_slave_start        | 0     |
| Com_slave_stop         | 0     |
| Slave_open_temp_tables | 0     |
+------------------------+-------+
5 rows in set (0.00 sec)

Empty set (0.00 sec)

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NONBLOCKING' at line 1
[14 Nov 2018 9:43] MySQL Verification Team
Hello Jean-François,

Thank you for the report and feedback!

regards,
Umesh
[8 Jan 2019 4:40] Paul DuBois
Posted by developer:
 
The Com_show_new_master status variable was removed in MySQL 5.5.11/5.6.2.

The Com_show_slave_status_nonblocking status variable was added in 5.7.0 and removed in 5.7.6.

I'll adjust the docs accordingly.