@Override
  public void close() {
    try {
      compactingScanner.close();
    } catch (IOException e) {
      LOG.warn("close store scanner failed", e);
    }
    compactingScanner = null;
    kvs.clear();
  }
The MemStoreCompactorSegmentsIterator extends MemStoreSegmentsIterator and performs the scan for
compaction operation meaning it is based on SQM
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreCompactorSegmentsIterator.java