Bug #73413 Manual does not explain MTS implementation in details
Submitted: 28 Jul 2014 16:33 Modified: 1 Aug 2014 9:45
Reporter: Valeriy Kravchuk Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Documentation Severity:S2 (Serious)
Version:5.6, 5.7 OS:Any
Assigned to: David Moss CPU Architecture:Any
Tags: missing manual, MTS, multi-threaded slave

[28 Jul 2014 16:33] Valeriy Kravchuk
Description:
Manual page on replication implementation details (http://dev.mysql.com/doc/refman/5.6/en/replication-implementation-details.html) does NOT provide any details on how multi-threaded implementation works, what threads are involved, how they are presented in the PROCESSLIST etc. Same manual page for 5.7 adds no details as well, while feature is even more advanced.

There is even no reference to http://dev.mysql.com/doc/refman/5.6/en/replication-options-slave.html#option_mysqld_slave-... explaining what defines how many threads are used actually.

How to repeat:
Try to find out in the manual what threads are created for multi-threaded slave, what are their typical statuses, does replication event format (ROW vs STATEMENT) matter for MTS or not, and so on.

Suggested fix:
Please, document everything related to multi-threaded slave feature in details, both for 5.6 and 5.7
[28 Jul 2014 20:28] Miguel Solorzano
Thank you for the bug report.
[29 Jul 2014 15:16] Sinisa Milivojevic
There is not a single doubt in my mind that this is truly a fully verified bug for the Server Documentation. I would have only preferred if the, highly esteemed, bug reporter was much more verbose and detailed as to how he would like to see a chapter on MTS and what various data it should contain.
[1 Aug 2014 9:45] Valeriy Kravchuk
I think I've explained why I personally miss (and thus want to see documented):

"Try to find out in the manual what threads are created for
multi-threaded slave, what are their typical statuses, does replication
event format (ROW vs STATEMENT) matter for MTS or not"

All threads involved in usual replication are documented, with their functions explained, on the page I mentioned initially.

I'd probably be able to suggest specific texts to add, but that would be a contribution and I don't have OCA signed (or even a permission from my managers to sign it). There is also no good reason to contribute specific texts for the manual while it is NOT open source. People prefer to write blog posts or contribute to knowledge bases like MariaDB one...