C++ (Cpp) ICostModel::GetCostModelParams Examples

Example #1

File: CCostTest.cpp Project: b-xiang/gporca

//---------------------------------------------------------------------------
//	@function:
//		CCostTest::EresUnittest_SetParams
//
//	@doc:
//		Test of setting cost model params
//
//---------------------------------------------------------------------------
GPOS_RESULT
CCostTest::EresUnittest_SetParams()
{
	CAutoMemoryPool amp;
	IMemoryPool *mp = amp.Pmp();

	// setup a file-based provider
	CMDProviderMemory *pmdp = CTestUtils::m_pmdpf;
	pmdp->AddRef();
	CMDAccessor mda(mp, CMDCache::Pcache(), CTestUtils::m_sysidDefault, pmdp);

	ICostModel *pcm = GPOS_NEW(mp) CCostModelGPDB(mp, GPOPT_TEST_SEGMENTS);

	// install opt context in TLS
	CAutoOptCtxt aoc(mp, &mda, NULL, /* pceeval */ pcm);

	// generate in-equality join expression
	CExpression *pexprOuter = CTestUtils::PexprLogicalGet(mp);
	const CColRef *pcrOuter = CDrvdPropRelational::GetRelationalProperties(pexprOuter->PdpDerive())->PcrsOutput()->PcrAny();
	CExpression *pexprInner = CTestUtils::PexprLogicalGet(mp);
	const CColRef *pcrInner = CDrvdPropRelational::GetRelationalProperties(pexprInner->PdpDerive())->PcrsOutput()->PcrAny();
	CExpression *pexprPred = CUtils::PexprScalarCmp(mp, pcrOuter, pcrInner, IMDType::EcmptNEq);
	CExpression *pexpr = CUtils::PexprLogicalJoin<CLogicalInnerJoin>(mp, pexprOuter, pexprInner, pexprPred);

	// optimize in-equality join based on default cost model params
	CExpression *pexprPlan1 = NULL;
	{
		CEngine eng(mp);

		// generate query context
		CQueryContext *pqc = CTestUtils::PqcGenerate(mp, pexpr);

		// Initialize engine
		eng.Init(pqc, NULL /*search_stage_array*/);

		// optimize query
		eng.Optimize();

		// extract plan
		pexprPlan1 = eng.PexprExtractPlan();
		GPOS_ASSERT(NULL != pexprPlan1);

		GPOS_DELETE(pqc);
	}

	// change NLJ cost factor
	ICostModelParams::SCostParam *pcp = pcm->GetCostModelParams()->PcpLookup(CCostModelParamsGPDB::EcpNLJFactor);
	CDouble dNLJFactor = CDouble(2.0);
	CDouble dVal = pcp->Get() * dNLJFactor;
	pcm->GetCostModelParams()->SetParam(pcp->Id(), dVal, dVal - 0.5, dVal + 0.5);

	// optimize again after updating NLJ cost factor
	CExpression *pexprPlan2 = NULL;
	{
		CEngine eng(mp);

		// generate query context
		CQueryContext *pqc = CTestUtils::PqcGenerate(mp, pexpr);

		// Initialize engine
		eng.Init(pqc, NULL /*search_stage_array*/);

		// optimize query
		eng.Optimize();

		// extract plan
		pexprPlan2 = eng.PexprExtractPlan();
		GPOS_ASSERT(NULL != pexprPlan2);

		GPOS_DELETE(pqc);
	}

	{
		CAutoTrace at(mp);
		at.Os() << "\nPLAN1: \n" << *pexprPlan1;
		at.Os() << "\nNLJ Cost1: " << (*pexprPlan1)[0]->Cost();
		at.Os() << "\n\nPLAN2: \n" << *pexprPlan2;
		at.Os() << "\nNLJ Cost2: " << (*pexprPlan2)[0]->Cost();
	}
	GPOS_ASSERT((*pexprPlan2)[0]->Cost() >= (*pexprPlan1)[0]->Cost() * dNLJFactor &&
			"expected NLJ cost in PLAN2 to be larger than NLJ cost in PLAN1");

	// clean up
	pexpr->Release();
	pexprPlan1->Release();
	pexprPlan2->Release();

	return GPOS_OK;
}