mariadb-columnstore-engine/utils/windowfunction/wf_ranking.cpp

/* 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: wf_ranking.cpp 3932 2013-06-25 16:08:10Z xlou $

// #define NDEBUG
#include <cmath>
using namespace std;

#include <boost/shared_ptr.hpp>
using namespace boost;

#include "loggingid.h"
using namespace logging;

#include "idborderby.h"
using namespace ordering;

using namespace execplan;

#include "windowfunctionstep.h"
using namespace joblist;

#include "wf_ranking.h"

namespace windowfunction
{
boost::shared_ptr<WindowFunctionType> WF_ranking::makeFunction(int id, const string& name, int /*ct*/,
                                                               WindowFunctionColumn* /*wc*/)
{
  boost::shared_ptr<WindowFunctionType> func(new WF_ranking(id, name));
  return func;
}

WindowFunctionType* WF_ranking::clone() const
{
  return new WF_ranking(*this);
}

void WF_ranking::resetData()
{
  fRank = 0;
  fDups = 0;

  WindowFunctionType::resetData();
}

void WF_ranking::operator()(int64_t b, int64_t e, int64_t c)
{
  // one row handling
  if (fPartition.first == fPartition.second)
  {
    fRow.setData(getPointer(fRowData->at(fPartition.first)));
    int64_t r = (fFunctionId == WF__PERCENT_RANK) ? 0 : 1;

    if (fFunctionId == WF__RANK || fFunctionId == WF__DENSE_RANK)
      setIntValue(fFieldIndex[0], r);
    else
      setDoubleValue(fFieldIndex[0], r);

    return;
  }

  // more than one row, e > b
  b = fPartition.first;
  e = fPartition.second;
  double n1 = e - b;  // count(*) - 1, n will not be 0.

  for (c = b; c <= e; c++)
  {
    if (c % 1000 == 0 && fStep->cancelled())
      break;

    if (c != b && fPeer->operator()(getPointer(fRowData->at(c)), getPointer(fRowData->at(c - 1))))
    {
      fDups++;
    }
    else
    {
      fRank++;

      if (fFunctionId != WF__DENSE_RANK)
        fRank += fDups;

      fDups = 0;
    }

    fRow.setData(getPointer(fRowData->at(c)));

    if (fFunctionId != WF__PERCENT_RANK)
      setIntValue(fFieldIndex[0], fRank);
    else
      setDoubleValue(fFieldIndex[0], (fRank - 1) / n1);
  }

  // Two-pass, need to find peers.
  if (fFunctionId == WF__CUME_DIST)
  {
    int prevRank = ++fRank + fDups;  // hypothetical row at (e+1)
    double n0 = (e - b + 1);         // count(*)
    double cumeDist = 1;
    fRow.setData(getPointer(fRowData->at(e)));

    for (c = e; c >= b; c--)
    {
      if (c % 1000 == 0 && fStep->cancelled())
        break;

      fRow.setData(getPointer(fRowData->at(c)));
      int currRank = getIntValue(fFieldIndex[0]);

      if (currRank != prevRank)
      {
        cumeDist = ((double)(prevRank - 1)) / n0;
        prevRank = currRank;
      }

      setDoubleValue(fFieldIndex[0], cumeDist);
    }
  }
}

}  // namespace windowfunction