greenplumn CPhysicalNLJoin 源码

greenplumn CPhysicalNLJoin 代码

文件路径：/src/backend/gporca/libgpopt/src/operators/CPhysicalNLJoin.cpp

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2012 EMC Corp.
//
//	@filename:
//		CPhysicalNLJoin.cpp
//
//	@doc:
//		Implementation of base nested-loops join operator
//---------------------------------------------------------------------------

#include "gpopt/operators/CPhysicalNLJoin.h"

#include "gpos/base.h"

#include "gpopt/base/COptCtxt.h"
#include "gpopt/base/CRewindabilitySpec.h"
#include "gpopt/operators/CExpressionHandle.h"
#include "gpopt/operators/CPhysicalCorrelatedInLeftSemiNLJoin.h"
#include "gpopt/operators/CPhysicalCorrelatedInnerNLJoin.h"
#include "gpopt/operators/CPhysicalCorrelatedLeftOuterNLJoin.h"
#include "gpopt/operators/CPredicateUtils.h"

using namespace gpopt;


//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::CPhysicalNLJoin
//
//	@doc:
//		Ctor
//
//---------------------------------------------------------------------------
CPhysicalNLJoin::CPhysicalNLJoin(CMemoryPool *mp) : CPhysicalJoin(mp)
{
	// NLJ creates two partition propagation requests for children:
	// (0) push possible Dynamic Partition Elimination (DPE) predicates from join's predicate to
	//		outer child, since outer child executes first
	// (1) ignore DPE opportunities in join's predicate, and push incoming partition propagation
	//		request to both children,
	//		this request handles the case where the inner child needs to be broadcasted, which prevents
	//		DPE by outer child since a Motion operator gets in between PartitionSelector and DynamicScan

	SetPartPropagateRequests(2);
}


//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::~CPhysicalNLJoin
//
//	@doc:
//		Dtor
//
//---------------------------------------------------------------------------
CPhysicalNLJoin::~CPhysicalNLJoin() = default;


//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::PosRequired
//
//	@doc:
//		Compute required sort order of the n-th child
//
//---------------------------------------------------------------------------
COrderSpec *
CPhysicalNLJoin::PosRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
							 COrderSpec *posInput, ULONG child_index,
							 CDrvdPropArray *,	// pdrgpdpCtxt
							 ULONG				// ulOptReq
) const
{
	GPOS_ASSERT(
		child_index < 2 &&
		"Required sort order can be computed on the relational child only");

	if (0 == child_index)
	{
		return PosPropagateToOuter(mp, exprhdl, posInput);
	}

	return GPOS_NEW(mp) COrderSpec(mp);
}


//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::PrsRequired
//
//	@doc:
//		Compute required rewindability of the n-th child
//
//---------------------------------------------------------------------------
CRewindabilitySpec *
CPhysicalNLJoin::PrsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
							 CRewindabilitySpec *prsRequired, ULONG child_index,
							 CDrvdPropArray *pdrgpdpCtxt,
							 ULONG	// ulOptReq
) const
{
	GPOS_ASSERT(
		child_index < 2 &&
		"Required rewindability can be computed on the relational child only");

	// inner child has to be rewindable
	if (1 == child_index)
	{
		if (FFirstChildToOptimize(child_index))
		{
			// for index nested loop joins, inner child is optimized first
			return GPOS_NEW(mp) CRewindabilitySpec(
				CRewindabilitySpec::ErtRewindable, prsRequired->Emht(), true);
		}

		CRewindabilitySpec *prsOuter =
			CDrvdPropPlan::Pdpplan((*pdrgpdpCtxt)[0 /*outer child*/])->Prs();
		CRewindabilitySpec::EMotionHazardType motion_hazard =
			GPOS_FTRACE(EopttraceMotionHazardHandling) &&
					(prsOuter->HasMotionHazard() ||
					 prsRequired->HasMotionHazard())
				? CRewindabilitySpec::EmhtMotion
				: CRewindabilitySpec::EmhtNoMotion;

		return GPOS_NEW(mp) CRewindabilitySpec(
			CRewindabilitySpec::ErtRewindable, motion_hazard, true);
	}

	GPOS_ASSERT(0 == child_index);

	return PrsPassThru(mp, exprhdl, prsRequired, 0 /*child_index*/);
}

//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::PcrsRequired
//
//	@doc:
//		Compute required output columns of n-th child
//
//---------------------------------------------------------------------------
CColRefSet *
CPhysicalNLJoin::PcrsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
							  CColRefSet *pcrsRequired, ULONG child_index,
							  CDrvdPropArray *,	 // pdrgpdpCtxt
							  ULONG				 // ulOptReq
)
{
	GPOS_ASSERT(
		child_index < 2 &&
		"Required properties can only be computed on the relational child");

	CColRefSet *pcrs = GPOS_NEW(mp) CColRefSet(mp);
	pcrs->Include(pcrsRequired);

	// For subqueries in the projection list, the required columns from the outer child
	// are often pushed down to the inner child and are not visible at the top level
	// so we can use the outer refs of the inner child as required from outer child
	if (0 == child_index)
	{
		CColRefSet *outer_refs = exprhdl.DeriveOuterReferences(1);
		pcrs->Include(outer_refs);
	}

	// request inner child of correlated join to provide required inner columns
	if (1 == child_index && FCorrelated())
	{
		pcrs->Include(PdrgPcrInner());
	}

	CColRefSet *pcrsReqd =
		PcrsChildReqd(mp, exprhdl, pcrs, child_index, 2 /*ulScalarIndex*/);
	pcrs->Release();

	return pcrsReqd;
}

//---------------------------------------------------------------------------
//	@function:
//		CPhysicalNLJoin::EpetOrder
//
//	@doc:
//		Return the enforcing type for order property based on this operator;
//
//
//---------------------------------------------------------------------------
CEnfdProp::EPropEnforcingType
CPhysicalNLJoin::EpetOrder(CExpressionHandle &exprhdl,
						   const CEnfdOrder *peo) const
{
	GPOS_ASSERT(nullptr != peo);
	GPOS_ASSERT(!peo->PosRequired()->IsEmpty());

	if (FSortColsInOuterChild(m_mp, exprhdl, peo->PosRequired()))
	{
		return CEnfdProp::EpetOptional;
	}

	return CEnfdProp::EpetRequired;
}


// EOF

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