@Override
  public synchronized void deleteSegment(short segId) throws SegmentNotFoundException {
    spareSize += getSegmentSize(segId);
    getSegment(segId).delete();
    segCacheMap.remove(segId);
    segOffsetLst.set(segId, (short) -1);
  }
Implementing marking deletion will not modify {@linkplain #memberNum} nor truncate {@linkplain
#segOffsetLst}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/pbtree/schemafile/SegmentedPage.java