Best practice for updating fields for a log message

I have a scenario where i need user to update field for a log entry which is stored in elastic search. Field size and data type is well defined. What are best practice around this? Does ES re-index that message? Can we query the new field? Can i stop re-indexing of the message after update to avoid cpu issue? Thanks!

Does ES re-index that message?

Yes.

Can we query the new field?

Yes.

Can i stop re-indexing of the message after update to avoid cpu issue?

What issue would that be?