CardinalityEstimator.h File Reference

Estimators to be used when precise cardinality isn't useful. More...

#include "RelAlgExecutionUnit.h"
#include "../Analyzer/Analyzer.h"
#include "Logger/Logger.h"

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Classes
class	CardinalityEstimationRequired
class	Analyzer::Estimator
class	Analyzer::NDVEstimator
class	Analyzer::LargeNDVEstimator

Namespaces
	Analyzer

Functions
RelAlgExecutionUnit	create_ndv_execution_unit (const RelAlgExecutionUnit &ra_exe_unit, const int64_t range)
RelAlgExecutionUnit	create_count_all_execution_unit (const RelAlgExecutionUnit &ra_exe_unit, std::shared_ptr< Analyzer::Expr > replacement_target)
ResultSetPtr	reduce_estimator_results (const RelAlgExecutionUnit &ra_exe_unit, std::vector< std::pair< ResultSetPtr, std::vector< size_t >>> &results_per_device)

Detailed Description

Estimators to be used when precise cardinality isn't useful.

Author

Alex Suhan alex@.nosp@m.mapd.nosp@m..com Copyright (c) 2016 MapD Technologies, Inc. All rights reserved.

Definition in file CardinalityEstimator.h.

Function Documentation

RelAlgExecutionUnit create_count_all_execution_unit	(	const RelAlgExecutionUnit &	ra_exe_unit,
		std::shared_ptr< Analyzer::Expr >	replacement_target
	)

Definition at line 104 of file CardinalityEstimator.cpp.

References Default, RelAlgExecutionUnit::input_col_descs, RelAlgExecutionUnit::input_descs, RelAlgExecutionUnit::join_quals, RelAlgExecutionUnit::quals, RelAlgExecutionUnit::query_state, RelAlgExecutionUnit::simple_quals, strip_join_covered_filter_quals(), and RelAlgExecutionUnit::union_all.

Referenced by RelAlgExecutor::getFilteredCountAll().

                                                    {
  return {ra_exe_unit.input_descs,
          ra_exe_unit.input_col_descs,
          ra_exe_unit.simple_quals,
          strip_join_covered_filter_quals(ra_exe_unit.quals, ra_exe_unit.join_quals),
          ra_exe_unit.join_quals,
          {},
          {replacement_target.get()},
          nullptr,
          SortInfo{{}, SortAlgorithm::Default, 0, 0},
          0,
          false,
          ra_exe_unit.union_all,
          ra_exe_unit.query_state};
}

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RelAlgExecutionUnit create_ndv_execution_unit	(	const RelAlgExecutionUnit &	ra_exe_unit,
		const int64_t	range
	)

Definition at line 85 of file CardinalityEstimator.cpp.

References Default, g_large_ndv_threshold, RelAlgExecutionUnit::groupby_exprs, RelAlgExecutionUnit::input_col_descs, RelAlgExecutionUnit::input_descs, RelAlgExecutionUnit::join_quals, RelAlgExecutionUnit::quals, RelAlgExecutionUnit::query_state, RelAlgExecutionUnit::simple_quals, and RelAlgExecutionUnit::union_all.

Referenced by RelAlgExecutor::getNDVEstimation().

                                                                   {
  return {ra_exe_unit.input_descs,
          ra_exe_unit.input_col_descs,
          ra_exe_unit.simple_quals,
          ra_exe_unit.quals,
          ra_exe_unit.join_quals,
          {},
          {},
          range > g_large_ndv_threshold
              ? makeExpr<Analyzer::LargeNDVEstimator>(ra_exe_unit.groupby_exprs)
              : makeExpr<Analyzer::NDVEstimator>(ra_exe_unit.groupby_exprs),
          SortInfo{{}, SortAlgorithm::Default, 0, 0},
          0,
          false,
          ra_exe_unit.union_all,
          ra_exe_unit.query_state};
}

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ResultSetPtr reduce_estimator_results	(	const RelAlgExecutionUnit &	ra_exe_unit,
		std::vector< std::pair< ResultSetPtr, std::vector< size_t >>> &	results_per_device
	)

Definition at line 122 of file CardinalityEstimator.cpp.

References CHECK, and RelAlgExecutionUnit::estimator.

Referenced by Executor::reduceMultiDeviceResults().

                                                                             {
  if (results_per_device.empty()) {
    return nullptr;
  }
  CHECK(dynamic_cast<const Analyzer::NDVEstimator*>(ra_exe_unit.estimator.get()));
  const auto& result_set = results_per_device.front().first;
  CHECK(result_set);
  auto estimator_buffer = result_set->getHostEstimatorBuffer();
  CHECK(estimator_buffer);
  for (size_t i = 1; i < results_per_device.size(); ++i) {
    const auto& next_result_set = results_per_device[i].first;
    const auto other_estimator_buffer = next_result_set->getHostEstimatorBuffer();
    for (size_t off = 0; off < ra_exe_unit.estimator->getBufferSize(); ++off) {
      estimator_buffer[off] |= other_estimator_buffer[off];
    }
  }
  return std::move(result_set);
}

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