@Override
  protected TsFileSequenceReader getReader(String filePath) throws IOException {
    return new CompactionTsFileReader(filePath, CompactionType.CROSS_COMPACTION);
  }
Estimate the memory cost of one cross space compaction task with specific source files based on
its corresponding implementation.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/compaction/selector/estimator/AbstractCrossSpaceEstimator.java