greenplumn CDefaultComparator 源码

greenplumn CDefaultComparator 代码

文件路径：/src/backend/gporca/libgpopt/src/base/CDefaultComparator.cpp

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2014 VMware, Inc. or its affiliates.
//
//	@filename:
//		CDefaultComparator.cpp
//
//	@doc:
//		Default comparator for IDatum instances to be used in constraint derivation
//
//	@owner:
//
//
//	@test:
//
//---------------------------------------------------------------------------

#include "gpopt/base/CDefaultComparator.h"

#include "gpos/memory/CAutoMemoryPool.h"

#include "gpopt/base/COptCtxt.h"
#include "gpopt/base/CUtils.h"
#include "gpopt/eval/IConstExprEvaluator.h"
#include "gpopt/exception.h"
#include "gpopt/mdcache/CMDAccessor.h"
#include "naucrates/base/IDatum.h"
#include "naucrates/base/IDatumBool.h"
#include "naucrates/md/IMDId.h"
#include "naucrates/md/IMDType.h"

using namespace gpopt;
using namespace gpos;
using gpnaucrates::IDatum;

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::CDefaultComparator
//
//	@doc:
//		Ctor
//		Does not take ownership of the constant expression evaluator
//
//---------------------------------------------------------------------------
CDefaultComparator::CDefaultComparator(IConstExprEvaluator *pceeval)
	: m_pceeval(pceeval)
{
	GPOS_ASSERT(nullptr != pceeval);
}

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::PexprEvalComparison
//
//	@doc:
//		Constructs a comparison expression of type cmp_type between the two given
//		data and evaluates it.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::FEvalComparison(CMemoryPool *mp, const IDatum *datum1,
									const IDatum *datum2,
									IMDType::ECmpType cmp_type) const
{
	GPOS_ASSERT(m_pceeval->FCanEvalExpressions());

	IDatum *pdatum1Copy = datum1->MakeCopy(mp);
	CExpression *pexpr1 = GPOS_NEW(mp)
		CExpression(mp, GPOS_NEW(mp) CScalarConst(mp, pdatum1Copy));
	IDatum *pdatum2Copy = datum2->MakeCopy(mp);
	CExpression *pexpr2 = GPOS_NEW(mp)
		CExpression(mp, GPOS_NEW(mp) CScalarConst(mp, pdatum2Copy));
	CExpression *pexprComp =
		CUtils::PexprScalarCmp(mp, pexpr1, pexpr2, cmp_type);

	CExpression *pexprResult = m_pceeval->PexprEval(pexprComp);
	pexprComp->Release();
	CScalarConst *popScalarConst = CScalarConst::PopConvert(pexprResult->Pop());
	IDatum *datum = popScalarConst->GetDatum();

	GPOS_ASSERT(IMDType::EtiBool == datum->GetDatumType());
	IDatumBool *pdatumBool = dynamic_cast<IDatumBool *>(datum);
	BOOL result = pdatumBool->GetValue();
	pexprResult->Release();

	return result;
}

BOOL
CDefaultComparator::FUseInternalEvaluator(const IDatum *datum1,
										  const IDatum *datum2,
										  BOOL *can_use_external_evaluator)
{
	IMDId *mdid1 = datum1->MDId();
	IMDId *mdid2 = datum2->MDId();

	// be conservative for now and require this extra condition that
	// has been in place for a while (might be relaxed in the future)
	*can_use_external_evaluator =
		GPOS_FTRACE(EopttraceEnableConstantExpressionEvaluation) &&
		CUtils::FConstrainableType(mdid1) && CUtils::FConstrainableType(mdid2);

	if (CUtils::FIntType(mdid1) && CUtils::FIntType(mdid2) &&
		!(*can_use_external_evaluator &&
		  GPOS_FTRACE(EopttraceUseExternalConstantExpressionEvaluationForInts)))
	{
		// INT types can be processed precisely by the internal evaluator
		return true;
	}

	// For now, specifically target date and timestamp columns, since they
	// are mappable to a double value that represents the number of microseconds
	// since Jan 1, 2000 and therefore those can be compared precisely, just like
	// integer types. Same goes for float types, since they map naturally to a
	// double value
	if (mdid1->Equals(datum2->MDId()) && datum1->StatsAreComparable(datum2) &&
		(CMDIdGPDB::m_mdid_date.Equals(mdid1) ||
		 CMDIdGPDB::m_mdid_time.Equals(mdid1) ||
		 CMDIdGPDB::m_mdid_timestamp.Equals(mdid1) ||
		 CMDIdGPDB::m_mdid_float4.Equals(mdid1) ||
		 CMDIdGPDB::m_mdid_float8.Equals(mdid1) ||
		 CMDIdGPDB::m_mdid_numeric.Equals(mdid1)))
	{
		return true;
	}

	// GPDB_12_MERGE_FIXME: Throw an exception when result = false and can_use_external_evaluator = false

	return false;
}


//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::Equals
//
//	@doc:
//		Tests if the two arguments are equal.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::Equals(const IDatum *datum1, const IDatum *datum2) const
{
	BOOL can_use_external_evaluator = false;

	if (FUseInternalEvaluator(datum1, datum2, &can_use_external_evaluator))
	{
		return datum1->StatsAreEqual(datum2);
	}

	if (!can_use_external_evaluator)
	{
		return false;
	}

	CAutoMemoryPool amp;

	// NULL datum is a special case and is being handled here. Assumptions made are
	// NULL is less than everything else. NULL = NULL.
	// Note : NULL is considered equal to NULL because we are using the comparator for
	//        interval calculation.
	if (datum1->IsNull() && datum2->IsNull())
	{
		return true;
	}

	return FEvalComparison(amp.Pmp(), datum1, datum2, IMDType::EcmptEq);
}

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::IsLessThan
//
//	@doc:
//		Tests if the first argument is less than the second.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::IsLessThan(const IDatum *datum1, const IDatum *datum2) const
{
	BOOL can_use_external_evaluator = false;

	if (FUseInternalEvaluator(datum1, datum2, &can_use_external_evaluator))
	{
		return datum1->StatsAreLessThan(datum2);
	}

	if (!can_use_external_evaluator)
	{
		return false;
	}

	CAutoMemoryPool amp;

	// NULL datum is a special case and is being handled here. Assumptions made are
	// NULL is less than everything else. NULL = NULL.
	// Note : NULL is considered equal to NULL because we are using the comparator for
	//        interval calculation.
	if (datum1->IsNull() && !datum2->IsNull())
	{
		return true;
	}

	return FEvalComparison(amp.Pmp(), datum1, datum2, IMDType::EcmptL);
}

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::IsLessThanOrEqual
//
//	@doc:
//		Tests if the first argument is less than or equal to the second.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::IsLessThanOrEqual(const IDatum *datum1,
									  const IDatum *datum2) const
{
	BOOL can_use_external_evaluator = false;

	if (FUseInternalEvaluator(datum1, datum2, &can_use_external_evaluator))
	{
		return datum1->StatsAreLessThan(datum2) ||
			   datum1->StatsAreEqual(datum2);
	}

	if (!can_use_external_evaluator)
	{
		return false;
	}

	CAutoMemoryPool amp;

	// NULL datum is a special case and is being handled here. Assumptions made are
	// NULL is less than everything else. NULL = NULL.
	// Note : NULL is considered equal to NULL because we are using the comparator for
	//        interval calculation.
	if (datum1->IsNull())
	{
		// return true since either:
		// 1. datum1 is NULL and datum2 is not NULL. Since NULL is considered
		// less that not null values for interval computations we return true
		// 2. when datum1 and datum2 are both NULL so they are equal
		// for interval computation

		return true;
	}


	return FEvalComparison(amp.Pmp(), datum1, datum2, IMDType::EcmptLEq);
}

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::IsGreaterThan
//
//	@doc:
//		Tests if the first argument is greater than the second.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::IsGreaterThan(const IDatum *datum1,
								  const IDatum *datum2) const
{
	BOOL can_use_external_evaluator = false;

	if (FUseInternalEvaluator(datum1, datum2, &can_use_external_evaluator))
	{
		return datum1->StatsAreGreaterThan(datum2);
	}

	if (!can_use_external_evaluator)
	{
		return false;
	}

	CAutoMemoryPool amp;

	// NULL datum is a special case and is being handled here. Assumptions made are
	// NULL is less than everything else. NULL = NULL.
	// Note : NULL is considered equal to NULL because we are using the comparator for
	//        interval calculation.
	if (!datum1->IsNull() && datum2->IsNull())
	{
		return true;
	}

	return FEvalComparison(amp.Pmp(), datum1, datum2, IMDType::EcmptG);
}

//---------------------------------------------------------------------------
//	@function:
//		CDefaultComparator::IsLessThanOrEqual
//
//	@doc:
//		Tests if the first argument is greater than or equal to the second.
//
//---------------------------------------------------------------------------
BOOL
CDefaultComparator::IsGreaterThanOrEqual(const IDatum *datum1,
										 const IDatum *datum2) const
{
	BOOL can_use_external_evaluator = false;

	if (FUseInternalEvaluator(datum1, datum2, &can_use_external_evaluator))
	{
		return datum1->StatsAreGreaterThan(datum2) ||
			   datum1->StatsAreEqual(datum2);
	}

	if (!can_use_external_evaluator)
	{
		return false;
	}

	CAutoMemoryPool amp;

	// NULL datum is a special case and is being handled here. Assumptions made are
	// NULL is less than everything else. NULL = NULL.
	// Note : NULL is considered equal to NULL because we are using the comparator for
	//        interval calculation.
	if (datum2->IsNull())
	{
		// return true since either:
		// 1. datum2 is NULL and datum1 is not NULL. Since NULL is considered
		// less that not null values for interval computations we return true
		// 2. when datum1 and datum2 are both NULL so they are equal
		// for interval computation
		return true;
	}

	return FEvalComparison(amp.Pmp(), datum1, datum2, IMDType::EcmptGEq);
}

// EOF

相关信息

greenplumn 源码目录

相关文章

greenplumn CAutoOptCtxt 源码

greenplumn CCTEInfo 源码

greenplumn CCTEMap 源码

greenplumn CCTEReq 源码

greenplumn CCastUtils 源码

greenplumn CColConstraintsArrayMapper 源码

greenplumn CColConstraintsHashMapper 源码

greenplumn CColRef 源码

greenplumn CColRefComputed 源码

greenplumn CColRefSet 源码