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101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
/* Copyright (C) 2014 InfiniDB, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/****************************************************************************
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* $Id: func_rand.cpp 3495 2013-01-21 14:09:51Z rdempsey $
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*
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*
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****************************************************************************/
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#include <cstdlib>
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#include <string>
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#include <sstream>
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using namespace std;
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#include "functor_export.h"
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#include "funchelpers.h"
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#include "functioncolumn.h"
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#include "rowgroup.h"
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#include "constantcolumn.h"
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using namespace execplan;
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#include "dataconvert.h"
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namespace funcexp
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{
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uint64_t maxValue = 0x3FFFFFFFL;
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/**
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* Follow MySQL's rand() implementation in item_func.cpp to guarantee compatibility
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*/
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double Func_rand::getRand()
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{
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uint64_t fSeed1_save = fSeed1;
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fSeed1 = (fSeed1 * 3 + fSeed2) % maxValue;
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// prevent the seed to repeat itself. e.g. seed1 = 1073741790; seed2 = 66;
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if (fSeed1_save == fSeed1)
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fSeed1 += 23;
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fSeed2 = (fSeed1 + fSeed2 + 33) % maxValue;
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return (((double)fSeed1) / (double)maxValue);
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}
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CalpontSystemCatalog::ColType Func_rand::operationType(FunctionParm& /*fp*/,
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CalpontSystemCatalog::ColType& resultType)
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{
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return resultType;
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}
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double Func_rand::getDoubleVal(rowgroup::Row& row, FunctionParm& parm, bool& isNull,
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execplan::CalpontSystemCatalog::ColType& /*op_ct*/)
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{
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// NOTE: this function needs to use 32bit ints otherwise it will break for negative values
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uint32_t seedParm = 0;
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// rand with parameter. if the parm is constanct, then a column is attached for fetching
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if (parm.size() == 1 || parm.size() == 2)
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{
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execplan::ConstantColumn* cc = dynamic_cast<execplan::ConstantColumn*>(parm[0].get()->data());
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if (!fSeedSet || !cc)
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{
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/* Copied from item_func.cpp */
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seedParm = parm[0]->data()->getIntVal(row, isNull);
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fSeed1 = (uint32_t)(seedParm * 0x10001L + 55555555L);
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fSeed2 = (uint32_t)(seedParm * 0x10000001L);
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fSeedSet = true;
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}
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}
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// rand without parameter. thd->rand are passed in. The 3rd is a simple column for fetching
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else
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{
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idbassert(parm.size() == 3);
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if (fSeedSet)
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{
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fSeed1 = parm[0]->data()->getIntVal(row, isNull);
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fSeed2 = parm[1]->data()->getIntVal(row, isNull);
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fSeedSet = true;
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}
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}
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return getRand();
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}
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} // namespace funcexp
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