question: private void compactGroups ( ) { for ( int i = 0 ; i < groups . size ( ) ; i ++ ) { List < Segment > group = groups . get ( i ) ; List < OffsetPredicate > groupPredicates = predicates . get ( i ) ; Segment segment = compactGroup ( group , groupPredicates ) ; mergeReleased ( group , groupPredicates , segment ) ; deleteGroup ( group ) ; } }
target:  Compacts all compactable segments.