mariadb-columnstore-engine/dbcon/joblist/rowestimator.h

/* Copyright (C) 2014 InfiniDB, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; version 2 of
   the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/***********************************************************************
 *   $Id: rowestimator.h 5449 2009-06-19 19:58:27Z wweeks $
 *
 *
 ***********************************************************************/
/** @file */

#pragma once

#include <boost/shared_ptr.hpp>
#include "joblisttypes.h"
#include "calpontsystemcatalog.h"
#include "columncommand-jl.h"
#include "brmtypes.h"
#include "bytestream.h"
#include <iostream>
#include <vector>
#include "brm.h"

namespace joblist
{
/** @brief estimates row counts for a TupleBPS.
 *
 * Class RowEstimator uses Casual Partitioning information and the filter string pertaining to a particular
 * TupleBPS object to estimate cardinality.  It is used to determine which table to use as the large side
 * table in a multijoin operation.
 */
class RowEstimator
{
 public:
  /** @brief ctor
   */
  RowEstimator() : fExtentsToSample(20)
  {
  }

  /** @brief estimate the number of rows that will be returned for a particular tuple batch primitive step.
   *
   * @param cpColVec  vector of ColumnCommandJL pointers associated to the step.
   * @param scanFlags vector of flags with one entry per extent populated by the casual
   *        partitioning evaluation, each that will be scanned are true, the ones that
   *        were eliminated by casual partitioining are false.
   * @param dbrm      DBRM object used to get the HWM.
   * @parm oid	   The objectid for the first column in the step.
   *
   */
  uint64_t estimateRows(const std::vector<ColumnCommandJL*>& cpColVec, const std::vector<bool>& scanFlags,
                        BRM::DBRM& dbrm, const execplan::CalpontSystemCatalog::OID oid);

  /** @brief Estimate the number of rows that will be returned for a particular table given
   *          a ColumnCommandJL for non casual partitioning column.  Added for bug 3503.
   *
   * @param colCmd The ColumnCommandJL.
   *
   */
  uint64_t estimateRowsForNonCPColumn(ColumnCommandJL& colCmd);

 private:
  /** @brief adjusts column values so that they can be compared via ranges.
   *
   * This function provides a value for dates, datetimes, and strings that can be used for distinct value
   * estimation and comparisons.
   *
   * @param ct	The column type.
   * @param value	The column value.
   *
   */
  uint64_t adjustValue(const execplan::CalpontSystemCatalog::ColType& ct, const uint64_t& value);

  uint32_t daysThroughMonth(uint32_t mth);

  template <typename T>
  uint32_t estimateDistinctValues(const execplan::CalpontSystemCatalog::ColType& ct, const T& min,
                                  const T& max, const char cpStatus);

  /** @brief returns a factor between 0 and 1 for the estimate of rows that will qualify the given individual
   * operation.
   *
   * This function works for a single operation such as "col1 = 5".
   *
   * @param ct	 The column type.
   * @param min	 The minimum value in the range.
   * @param max	 The maximum value in the range.
   * @parm cpStatus The status of the CP data (whether it's valid).
   *
   */
  template <class T>
  float estimateOpFactor(const T& min, const T& max, const T& value, char op, uint8_t lcf,
                         uint32_t distinctValues, char cpStatus,
                         const execplan::CalpontSystemCatalog::ColType& ct);

  /** @brief returns a factor between 0 and 1 for the estimate of rows that will qualify
   *          the given operation(s).
   *
   * This function works for multiple operations against the same column such as
   * "col1 = 5 or col1 = 10".  It calls estimateOpFactor for each individual operation.
   *
   * @param emEntry      The extent map entry for the extent being evaluated.
   * @param msgDataPtr   The filter string.
   * @param ct	      The column type.
   * @param BOP	      The binary operator for the filter predicates (eg. OR for col1 = 5 or col1 = 10)
   * @param rowsInExtent The number of rows in the extent being evaluated.
   *
   */
  float estimateRowReturnFactor(const BRM::EMEntry& emEntry, const messageqcpp::ByteStream* msgDataPtr,
                                const uint16_t NOPS, const execplan::CalpontSystemCatalog::ColType& ct,
                                const uint8_t BOP, const uint32_t& rowsInExtent);

  // Configurables read from Columnstore.xml - future.
  uint32_t fExtentsToSample;

  static const uint32_t fRowsPerExtent = 8192 * 1024;
  static const uint32_t fBlockSize = 8192;  // Block size in bytes.

  // Limits the number of comparisons for each extent.  Example, in clause w/ 1000 values will limit the
  // checks to the number below.
  static const uint32_t fMaxComparisons = 10;

};  // RowEstimator

}  // namespace joblist