@Override
  public void purgeSegments() {
    segCacheMap.clear();
    segOffsetLst.clear();
    memberNum = 0;
    spareOffset = SchemaFileConfig.PAGE_HEADER_SIZE;
    spareSize = (short) (pageBuffer.capacity() - SchemaFileConfig.PAGE_HEADER_SIZE);
  }
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