You can update an existing lifecycle policy to fix mistakes or change
strategies for newly created indices. It is possible to update policy definitions
and an index’s
index.lifecycle.name settings independently. To prevent the situation
that phase definitions are modified while currently being executed on an index, each index
will keep the version of the current phase definition it began execution with until it completes.
There are three scenarios for examining the behavior updating policies and their effects on policy execution on indices.