public List<PipelineDriverFactory> getPipelineDriverFactories() {
    return pipelineDriverFactories;
  }
Each time we construct a pipeline, we should also construct the memory estimator for the
pipeline.

@param operation the root operator of the pipeline
@param parentPlanNodeId the parent plan node id of the root of the pipeline
@param root the root node of the pipeline
@param dependencyPipelineIndex the index of the dependency pipeline, -1 if no dependency
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/LocalExecutionPlanContext.java