Indicates the target size (at least the size of 1 minisegment) and time span (at least 1 day) covered by a merged segment, as a percentage of the retention byte and time limits. This decides the minimum desired merge-result segments based on retention size/time. If retention is less than 30 days, the default value means this has no effect, as targets are always allowed to be at least 1 day wide. But if retention-by-time is higher than 30 days, use this factor to determine the desired span of segments. Example: 120 day retention would result in segments targeting being 4 days wide (segments still get closed due to reaching max size too.)