@Override
  public CompactionState getCompactionState() {
    boolean hasMajor = majorInProgress.get() > 0, hasMinor = minorInProgress.get() > 0;
    return (hasMajor
      ? (hasMinor ? CompactionState.MAJOR_AND_MINOR : CompactionState.MAJOR)
      : (hasMinor ? CompactionState.MINOR : CompactionState.NONE));
  }
Returns the latest sequence number that was read from storage when this region was opened
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java