Live Config Changes

[Guyme]

What
Provide an interface to change configurable parameters on the fly even if the application does not support it

Why

• Improve user experience when tuning parameters during PoCs, testing and customer environment.
• Changing parameters without restarting the database

Who

• Testing
• Customers (production)
• POCs

Functional Requirements:

• The user should be able to change with this method mutable parameters only. This method cannot be used to change immutable parameters.
  Example: The user shall be able to load a config file, with similar format to the Options file and to call the appropriate rocksdb update option (pending RnD decision)
• The new option/s should be loaded on the fly without the need to reload/recompile the code.
• When changing a parameter, the old and new values should be printed to the log

[Yuval-Ariel]

we've agreed that using this feature with the stress test requires addition of injecting the "refresh options file". @mrambacher will this be included in this ticket or a subsequent one?