Port/merge the CHANGE MASTER TO ... MASTER_DELAY option from MySQL 5.6

Description

This feature was earlier a port-in-progress in the OurDelta builds, but wasn't included in the work for 5.1 that Monty and I did for MariaDB.
It's in stock MySQL 5.6. It's a useful feature, and clients still sometimes need it. The pt-slave-delay tool does the job, but it's nicer to have it in the server - and heck, the code already exists.

If we can get this merged into (for instance) 10.1, that'd be great.
thanks

Environment

None

Status

Assignee

Unassigned

Reporter

Arjen Lentz

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External issue ID

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External issue ID

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Time tracking

120h

Fix versions

Priority

Major