greenplumn CUpperBoundNDVs 源码
greenplumn CUpperBoundNDVs 代码
文件路径：/src/backend/gporca/libnaucrates/include/naucrates/statistics/CUpperBoundNDVs.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2014 VMware, Inc. or its affiliates.
//
// @filename:
// CUpperBoundNDVs.h
//
// @doc:
// Upper bound on the number of distinct values for a given set of columns
//---------------------------------------------------------------------------
#ifndef GPNAUCRATES_CUpperBoundNDVs_H
#define GPNAUCRATES_CUpperBoundNDVs_H
#include "gpos/base.h"
#include "gpopt/base/CColRefSet.h"
namespace gpnaucrates
{
using namespace gpos;
using namespace gpmd;
// forward decl
class CUpperBoundNDVs;
// dynamic array of upper bound ndvs
using CUpperBoundNDVPtrArray = CDynamicPtrArray<CUpperBoundNDVs, CleanupDelete>;
//---------------------------------------------------------------------------
// @class:
// CUpperBoundNDVs
//
// @doc:
// Upper bound on the number of distinct values for a given set of columns
//
//---------------------------------------------------------------------------
class CUpperBoundNDVs
{
private:
// set of column references
CColRefSet *m_column_refset;
// upper bound of ndvs
CDouble m_upper_bound_ndv;
public:
CUpperBoundNDVs(const CUpperBoundNDVs &) = delete;
// ctor
CUpperBoundNDVs(CColRefSet *column_refset, CDouble upper_bound_ndv)
: m_column_refset(column_refset), m_upper_bound_ndv(upper_bound_ndv)
{
GPOS_ASSERT(nullptr != m_column_refset);
}
// dtor
~CUpperBoundNDVs()
{
m_column_refset->Release();
}
// return the upper bound of ndvs
CDouble
UpperBoundNDVs() const
{
return m_upper_bound_ndv;
}
// check if the column is present
BOOL
IsPresent(const CColRef *column_ref) const
{
return m_column_refset->FMember(column_ref);
}
// copy upper bound ndvs
CUpperBoundNDVs *CopyUpperBoundNDVs(CMemoryPool *mp) const;
CUpperBoundNDVs *CopyUpperBoundNDVs(CMemoryPool *mp,
CDouble upper_bound_ndv) const;
// copy upper bound ndvs with remapped column id; function will
// return null if there is no mapping found for any of the columns
CUpperBoundNDVs *CopyUpperBoundNDVWithRemap(
CMemoryPool *mp, UlongToColRefMap *colid_to_colref_map) const;
// print function
IOstream &OsPrint(IOstream &os) const;
};
} // namespace gpnaucrates
#endif // !GPNAUCRATES_CUpperBoundNDVs_H
// EOF
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