greenplumn CDistributionSpecRandom 源码

greenplumn CDistributionSpecRandom 代码

文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CDistributionSpecRandom.h

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2011 EMC Corp.
//
//	@filename:
//		CDistributionSpecRandom.h
//
//	@doc:
//		Description of a forced random distribution;
//		Can be used as required or derived property;
//---------------------------------------------------------------------------
#ifndef GPOPT_CDistributionSpecRandom_H
#define GPOPT_CDistributionSpecRandom_H

#include "gpos/base.h"

#include "gpopt/base/CDistributionSpec.h"

namespace gpopt
{
using namespace gpos;

//---------------------------------------------------------------------------
//	@class:
//		CDistributionSpecRandom
//
//	@doc:
//		Class for representing forced random distribution.
//
//---------------------------------------------------------------------------
class CDistributionSpecRandom : public CDistributionSpec
{
protected:
	// is the random distribution sensitive to duplicates
	BOOL m_is_duplicate_sensitive{false};

	// does Singleton spec satisfy current distribution?
	// by default, Singleton satisfies hashed/random since all tuples with the same hash value
	// are moved to the same host/segment,
	// this flag adds the ability to mark a distribution request as non-satisfiable by Singleton
	// in case we need to enforce across segments distribution
	BOOL m_fSatisfiedBySingleton{true};

	// private copy ctor
	CDistributionSpecRandom(const CDistributionSpecRandom &);

	CColRef *m_gp_segment_id = {nullptr};

public:
	//ctor
	CDistributionSpecRandom();

	CDistributionSpecRandom(CColRef *gp_segment_id_);

	// accessor
	EDistributionType
	Edt() const override
	{
		return CDistributionSpec::EdtRandom;
	}

	virtual const CHAR *
	SzId() const
	{
		return "RANDOM";
	}

	// is distribution duplicate sensitive
	BOOL
	IsDuplicateSensitive() const
	{
		return m_is_duplicate_sensitive;
	}

	// mark distribution as unsatisfiable by Singleton
	void
	MarkDuplicateSensitive()
	{
		GPOS_ASSERT(!m_is_duplicate_sensitive);

		m_is_duplicate_sensitive = true;
	}

	// does Singleton spec satisfy current distribution?
	BOOL
	FSatisfiedBySingleton() const
	{
		return m_fSatisfiedBySingleton;
	}

	// mark distribution as unsatisfiable by Singleton
	void
	MarkUnsatisfiableBySingleton()
	{
		GPOS_ASSERT(m_fSatisfiedBySingleton);

		m_fSatisfiedBySingleton = false;
	}

	// does this distribution match the given one
	BOOL Matches(const CDistributionSpec *pds) const override;

	// does current 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;

	// return distribution partitioning type
	EDistributionPartitioningType
	Edpt() const override
	{
		return EdptPartitioned;
	}

	// print
	IOstream &OsPrint(IOstream &os) const override;

	// conversion function
	static CDistributionSpecRandom *
	PdsConvert(CDistributionSpec *pds)
	{
		GPOS_ASSERT(nullptr != pds);
		GPOS_ASSERT(EdtRandom == pds->Edt());

		return dynamic_cast<CDistributionSpecRandom *>(pds);
	}

	// conversion function: const argument
	static const CDistributionSpecRandom *
	PdsConvert(const CDistributionSpec *pds)
	{
		GPOS_ASSERT(nullptr != pds);
		GPOS_ASSERT(EdtRandom == pds->Edt());

		return dynamic_cast<const CDistributionSpecRandom *>(pds);
	}

};	// class CDistributionSpecRandom

}  // namespace gpopt

#endif	// !GPOPT_CDistributionSpecRandom_H

// EOF

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