This setting is only used with the forcemerged filtertype.
The value for this setting is the cutoff number of segments per shard. Indices
which have this number of segments per shard, or fewer, will be actionable
depending on the value of exclude, which is
True by default for
the forcemerged filter type.
There is no default value. This setting must be set by the user or an exception will be raised, and execution will halt.