greenplumn CDistributionSpecStrictSingleton 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CDistributionSpecStrictSingleton.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2013 EMC Corp.
/
/ @filename:
/ CDistributionSpecStrictSingleton.h
/
/ @doc:
/ Description of a strict singleton distribution. Unlike the simple singleton distribution,
/ that satisfies hash distribution requests, the strict singleton distribution is only
/ compatible with other singleton distributions
/ Can be used as a derived property;
/---------------------------------------------------------------------------
#ifndef GPOPT_CDistributionSpecStrictSingleton_H
#define GPOPT_CDistributionSpecStrictSingleton_H
#include "gpos/base.h"
#include "gpos/utils.h"
#include "gpopt/base/CDistributionSpecSingleton.h"
namespace gpopt
{
using namespace gpos;
/---------------------------------------------------------------------------
/ @class:
/ CDistributionSpecStrictSingleton
/
/ @doc:
/ Class for representing singleton distribution specification.
/
/---------------------------------------------------------------------------
class CDistributionSpecStrictSingleton : public CDistributionSpecSingleton
{
private:
public:
CDistributionSpecStrictSingleton(const CDistributionSpecStrictSingleton &) =
delete;
/ ctor
explicit CDistributionSpecStrictSingleton(ESegmentType esegtype);
/ distribution type accessor
EDistributionType
Edt() const override
{
return CDistributionSpec::EdtStrictSingleton;
}
/ return true if distribution spec can be required
BOOL
FRequirable() const override
{
return false;
}
/ does this distribution satisfy the given one
BOOL FSatisfies(const CDistributionSpec *pds) const override;
/ append enforcers to dynamic array for the given plan properties
void
AppendEnforcers(CMemoryPool *, / mp
CExpressionHandle &, / exprhdl
CReqdPropPlan *, / prpp
CExpressionArray *, / pdrgpexpr
CExpression * / pexpr
) override
{
GPOS_ASSERT(!"attempt to enforce strict SINGLETON distribution");
}
/ print
IOstream &OsPrint(IOstream &os) const override;
/ conversion function
static CDistributionSpecStrictSingleton *
PdssConvert(CDistributionSpec *pds)
{
GPOS_ASSERT(nullptr != pds);
GPOS_ASSERT(EdtStrictSingleton == pds->Edt());
return dynamic_cast<CDistributionSpecStrictSingleton *>(pds);
}
}; / class CDistributionSpecStrictSingleton
} / namespace gpopt
#endif / !GPOPT_CDistributionSpecStrictSingleton_H
/ EOF
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