[Refactor] Rename functions for clarity and add DbgPrints

Functions renamed:
- CHistogram::Buckets -> GetNumBuckets
- CHistogram::ParseDXLToBucketsArray -> GetBuckets

Implemented DbgPrint for:
- CBucket
- CHistogram
Co-authored-by: NAshuka Xue <axue@pivotal.io>
Co-authored-by: NShreedhar Hardikar <shardikar@pivotal.io>

src/backend/gpopt/translate/CTranslatorRelcacheToDXL.cpp

@@ -2959,7 +2959,7 @@ CTranslatorRelcacheToDXL::TransformStatsToDXLBucketArray
 						num_distinct,
 						hist_freq
 						);
-		if (0 == histogram->Buckets())
+		if (0 == histogram->GetNumBuckets())
 		{
 			has_hist = false;
 		}
@@ -3165,7 +3165,7 @@ CTranslatorRelcacheToDXL::TransformHistogramToDXLBucketArray
 	)
 {
 	CDXLBucketArray *dxl_stats_bucket_array = GPOS_NEW(mp) CDXLBucketArray(mp);
-	const CBucketArray *buckets = hist->ParseDXLToBucketsArray();
+	const CBucketArray *buckets = hist->GetBuckets();
 	ULONG num_buckets = buckets->Size();
 	for (ULONG ul = 0; ul < num_buckets; ul++)
 	{

src/backend/gporca/libnaucrates/include/naucrates/statistics/CBucket.h

@@ -13,6 +13,8 @@
 #define GPNAUCRATES_CBucket_H
 
 #include "gpos/base.h"
+#include "gpos/task/CTask.h"
+#include "gpos/error/CAutoTrace.h"
 #include "naucrates/statistics/CPoint.h"
 #include "naucrates/statistics/IBucket.h"
 
@@ -171,6 +173,10 @@ namespace gpnaucrates
 			virtual
 			IOstream &OsPrint(IOstream &os) const;
 
+#ifdef GPOS_DEBUG
+			void DbgPrint() const;
+#endif
+
 			// construct new bucket with lower bound greater than given point
 			CBucket *MakeBucketGreaterThan(CMemoryPool *mp, CPoint *point) const;
 

src/backend/gporca/libnaucrates/include/naucrates/statistics/CHistogram.h

@@ -348,13 +348,13 @@ namespace gpnaucrates
 					const;
 
 			// number of buckets
-			ULONG Buckets() const
+			ULONG GetNumBuckets() const
 			{
 				return m_histogram_buckets->Size();
 			}
 
 			// buckets accessor
-			const CBucketArray *ParseDXLToBucketsArray() const
+			const CBucketArray *GetBuckets() const
 			{
 				return m_histogram_buckets;
 			}
@@ -375,6 +375,10 @@ namespace gpnaucrates
 			virtual
 			IOstream &OsPrint(IOstream &os) const;
 
+#ifdef GPOS_DEBUG
+			void DbgPrint() const;
+#endif
+
 			// total frequency from buckets and null fraction
 			CDouble GetFrequency() const;
 

src/backend/gporca/libnaucrates/src/statistics/CBucket.cpp

@@ -246,6 +246,15 @@ CBucket::OsPrint
 	return os;
 }
 
+#ifdef GPOS_DEBUG
+void
+CBucket::DbgPrint() const
+{
+	CAutoTrace at(CTask::Self()->Pmp());
+	OsPrint(at.Os());
+}
+#endif
+
 //---------------------------------------------------------------------------
 //	@function:
 //		CBucket::MakeBucketGreaterThan

src/backend/gporca/libnaucrates/src/statistics/CHistogram.cpp

@@ -176,6 +176,15 @@ CHistogram::OsPrint
 	return os;
 }
 
+#ifdef GPOS_DEBUG
+void
+CHistogram::DbgPrint() const
+{
+	CAutoTrace at(CTask::Self()->Pmp());
+	OsPrint(at.Os());
+}
+#endif
+
 // check if histogram is empty
 BOOL
 CHistogram::IsEmpty
@@ -973,8 +982,8 @@ CHistogram::MakeLASJHistogram
 
 	CBucket *candidate_bucket = NULL;
 
-	const ULONG buckets1 = Buckets();
-	const ULONG buckets2 = histogram->Buckets();
+	const ULONG buckets1 = GetNumBuckets();
+	const ULONG buckets2 = histogram->GetNumBuckets();
 
 	while (idx1 < buckets1 && idx2 < buckets2)
 	{
@@ -1041,7 +1050,7 @@ CDouble
 CHistogram::NormalizeHistogram()
 {
 	// trivially normalized
-	if (Buckets() == 0 && CStatistics::Epsilon > m_null_freq && CStatistics::Epsilon > m_distinct_remaining)
+	if (GetNumBuckets() == 0 && CStatistics::Epsilon > m_null_freq && CStatistics::Epsilon > m_distinct_remaining)
 	{
 		return CDouble(GPOS_FP_ABS_MAX);
 	}
@@ -1156,8 +1165,8 @@ CHistogram::MakeJoinHistogramEqualityFilter
 	ULONG idx1 = 0; // index on buckets from this histogram
 	ULONG idx2 = 0; // index on buckets from other histogram
 
-	const ULONG buckets1 = Buckets();
-	const ULONG buckets2 = histogram->Buckets();
+	const ULONG buckets1 = GetNumBuckets();
+	const ULONG buckets2 = histogram->GetNumBuckets();
 
 	CDouble hist1_buckets_freq(0.0);
 	CDouble hist2_buckets_freq(0.0);
@@ -1323,8 +1332,8 @@ CHistogram::CanComputeJoinNDVRemain
 	GPOS_ASSERT(NULL != histogram1);
 	GPOS_ASSERT(NULL != histogram2);
 
-	BOOL has_buckets1 = (0 != histogram1->Buckets());
-	BOOL has_buckets2 = (0 != histogram2->Buckets());
+	BOOL has_buckets1 = (0 != histogram1->GetNumBuckets());
+	BOOL has_buckets2 = (0 != histogram2->GetNumBuckets());
 	BOOL has_distinct_remain1 = CStatistics::Epsilon < histogram1->GetDistinctRemain();
 	BOOL has_distinct_remain2 = CStatistics::Epsilon < histogram2->GetDistinctRemain();
 
@@ -1404,14 +1413,14 @@ CHistogram::ComputeJoinNDVRemainInfo
 	CDouble remaining_join_NDVs = std::max(final_join_NDVs - join_NDVs, CDouble(0.0));
 
 	// compute the frequency of the non-joining buckets in each input histogram
-	CDouble freq_buckets1 =  CStatisticsUtils::GetFrequency(histogram1->ParseDXLToBucketsArray());
-	CDouble freq_buckets2 =  CStatisticsUtils::GetFrequency(histogram2->ParseDXLToBucketsArray());
+	CDouble freq_buckets1 =  CStatisticsUtils::GetFrequency(histogram1->GetBuckets());
+	CDouble freq_buckets2 =  CStatisticsUtils::GetFrequency(histogram2->GetBuckets());
 	CDouble freq_non_join_buckets1 = std::max(CDouble(0), (freq_buckets1 - hist1_buckets_freq));
 	CDouble freq_non_join_buckets2 = std::max(CDouble(0), (freq_buckets2 - hist2_buckets_freq));
 
 	// compute the NDV of the non-joining buckets
-	CDouble NDVs_non_join_buckets1 = CStatisticsUtils::GetNumDistinct(histogram1->ParseDXLToBucketsArray()) - join_NDVs;
-	CDouble NDVs_non_join_buckets2 = CStatisticsUtils::GetNumDistinct(histogram2->ParseDXLToBucketsArray()) - join_NDVs;
+	CDouble NDVs_non_join_buckets1 = CStatisticsUtils::GetNumDistinct(histogram1->GetBuckets()) - join_NDVs;
+	CDouble NDVs_non_join_buckets2 = CStatisticsUtils::GetNumDistinct(histogram2->GetBuckets()) - join_NDVs;
 
 	CDouble freq_remain1 = histogram1->GetFreqRemain();
 	CDouble freq_remain2 = histogram2->GetFreqRemain();
@@ -1554,8 +1563,8 @@ CHistogram::MakeUnionAllHistogramNormalize
 		}
 	}
 
-	const ULONG buckets1 = Buckets();
-	const ULONG buckets2 = histogram->Buckets();
+	const ULONG buckets1 = GetNumBuckets();
+	const ULONG buckets2 = histogram->GetNumBuckets();
 
 	GPOS_ASSERT_IFF(NULL == bucket1, idx1 == buckets1);
 	GPOS_ASSERT_IFF(NULL == bucket2, idx2 == buckets2);
@@ -1751,8 +1760,8 @@ CHistogram::MakeUnionHistogramNormalize
 		}
 	}
 
-	const ULONG buckets1 = Buckets();
-	const ULONG buckets2 = other_histogram->Buckets();
+	const ULONG buckets1 = GetNumBuckets();
+	const ULONG buckets2 = other_histogram->GetNumBuckets();
 
 	GPOS_ASSERT_IFF(NULL == bucket1, idx1 == buckets1);
 	GPOS_ASSERT_IFF(NULL == bucket2, idx2 == buckets2);
@@ -1880,7 +1889,7 @@ CHistogram::operator []
 	)
 	const
 {
-	if (pos < Buckets())
+	if (pos < GetNumBuckets())
 	{
 		return (*m_histogram_buckets) [pos];
 	}
@@ -2067,13 +2076,13 @@ CHistogram::DoNDVBasedCardEstimation
 {
 	GPOS_ASSERT(NULL != histogram);
 
-	if (0 == histogram->Buckets())
+	if (0 == histogram->GetNumBuckets())
 	{
 		// no buckets, so join cardinality estimation is based solely on NDV remain
 		return true;
 	}
 
-	const IBucket *bucket = (*histogram->ParseDXLToBucketsArray())[0];
+	const IBucket *bucket = (*histogram->GetBuckets())[0];
 
 	IDatum *datum = bucket->GetLowerBound()->GetDatum();
 

src/backend/gporca/libnaucrates/src/statistics/CStatisticsUtils.cpp

@@ -188,11 +188,11 @@ CStatisticsUtils::MergeMCVHist
 	GPOS_ASSERT(NULL != histogram);
 	GPOS_ASSERT(mcv_histogram->IsWellDefined());
 	GPOS_ASSERT(histogram->IsWellDefined());
-	GPOS_ASSERT(0 < mcv_histogram->Buckets());
-	GPOS_ASSERT(0 < histogram->Buckets());
+	GPOS_ASSERT(0 < mcv_histogram->GetNumBuckets());
+	GPOS_ASSERT(0 < histogram->GetNumBuckets());
 
-	const CBucketArray *mcv_buckets = mcv_histogram->ParseDXLToBucketsArray();
-	const CBucketArray *histogram_buckets = histogram->ParseDXLToBucketsArray();
+	const CBucketArray *mcv_buckets = mcv_histogram->GetBuckets();
+	const CBucketArray *histogram_buckets = histogram->GetBuckets();
 
 	IDatum *datum = (*mcv_buckets)[0]->GetLowerBound()->GetDatum();
 

src/backend/gporca/server/src/unittest/dxl/statistics/CHistogramTest.cpp

@@ -71,24 +71,24 @@ CHistogramTest::EresUnittest_CHistogramInt4()
 	CPoint *ppoint0 = CTestUtils::PpointInt4(mp, 9);
 	CHistogram *phist0 = histogram->MakeHistogramFilter(CStatsPred::EstatscmptG, ppoint0);
 	CCardinalityTestUtils::PrintHist(mp, "phist0", phist0);
-	GPOS_RTL_ASSERT(phist0->Buckets() == 9);
+	GPOS_RTL_ASSERT(phist0->GetNumBuckets() == 9);
 
 	CPoint *point1 = CTestUtils::PpointInt4(mp, 35);
 	CHistogram *histogram1 = histogram->MakeHistogramFilter(CStatsPred::EstatscmptL, point1);
 	CCardinalityTestUtils::PrintHist(mp, "histogram1", histogram1);
-	GPOS_RTL_ASSERT(histogram1->Buckets() == 4);
+	GPOS_RTL_ASSERT(histogram1->GetNumBuckets() == 4);
 
 	// edge case where point is equal to upper bound
 	CPoint *point2 = CTestUtils::PpointInt4(mp, 50);
 	CHistogram *histogram2 = histogram->MakeHistogramFilter(CStatsPred::EstatscmptL,point2);
 	CCardinalityTestUtils::PrintHist(mp, "histogram2", histogram2);
-	GPOS_RTL_ASSERT(histogram2->Buckets() == 5);
+	GPOS_RTL_ASSERT(histogram2->GetNumBuckets() == 5);
 
 	// equality check
 	CPoint *point3 = CTestUtils::PpointInt4(mp, 100);
 	CHistogram *phist3 = histogram->MakeHistogramFilter(CStatsPred::EstatscmptEq, point3);
 	CCardinalityTestUtils::PrintHist(mp, "phist3", phist3);
-	GPOS_RTL_ASSERT(phist3->Buckets() == 1);
+	GPOS_RTL_ASSERT(phist3->GetNumBuckets() == 1);
 
 	// normalized output after filter
 	CPoint *ppoint4 = CTestUtils::PpointInt4(mp, 100);
@@ -100,12 +100,12 @@ CHistogramTest::EresUnittest_CHistogramInt4()
 	// lasj
 	CHistogram *phist5 = histogram->MakeLASJHistogram(CStatsPred::EstatscmptEq, histogram2);
 	CCardinalityTestUtils::PrintHist(mp, "phist5", phist5);
-	GPOS_RTL_ASSERT(phist5->Buckets() == 5);
+	GPOS_RTL_ASSERT(phist5->GetNumBuckets() == 5);
 
 	// inequality check
 	CHistogram *phist6 = histogram->MakeHistogramFilter(CStatsPred::EstatscmptNEq, point2);
 	CCardinalityTestUtils::PrintHist(mp, "phist6", phist6);
-	GPOS_RTL_ASSERT(phist6->Buckets() == 10);
+	GPOS_RTL_ASSERT(phist6->GetNumBuckets() == 10);
 
 	// histogram with null fraction and remaining tuples
 	CHistogram *phist7 = PhistExampleInt4Remain(mp);
@@ -125,7 +125,7 @@ CHistogramTest::EresUnittest_CHistogramInt4()
 
 	// equality join, hitting remaining tuples
 	CHistogram *phist10 = phist7->MakeJoinHistogram(CStatsPred::EstatscmptEq, phist7);
-	GPOS_RTL_ASSERT(phist10->Buckets() == 5);
+	GPOS_RTL_ASSERT(phist10->GetNumBuckets() == 5);
 	GPOS_RTL_ASSERT(fabs((phist10->GetDistinctRemain() - 2.0).Get()) < CStatistics::Epsilon);
 	GPOS_RTL_ASSERT(fabs((phist10->GetFreqRemain() - 0.08).Get()) < CStatistics::Epsilon);
 
@@ -173,7 +173,7 @@ CHistogramTest::EresUnittest_CHistogramBool()
 	CDouble scale_factor(0.0);
 	CHistogram *histogram1 = histogram->MakeHistogramFilterNormalize(CStatsPred::EstatscmptEq, point1, &scale_factor);
 	CCardinalityTestUtils::PrintHist(mp, "histogram1", histogram1);
-	GPOS_RTL_ASSERT(histogram1->Buckets() == 1);
+	GPOS_RTL_ASSERT(histogram1->GetNumBuckets() == 1);
 
 	// clean up
 	point1->Release();

src/backend/gporca/server/src/unittest/dxl/statistics/CJoinCardinalityTest.cpp

@@ -160,11 +160,11 @@ CJoinCardinalityTest::EresUnittest_JoinNDVRemain()
 		CDouble dNDVRemainJoin = elem.m_dNDVRemainJoin;
 		CDouble dFreqRemainJoin = elem.m_dFreqRemainJoin;
 
-		CDouble dDiffNDVJoin(fabs((dNDVBucketsJoin - CStatisticsUtils::GetNumDistinct(join_histogram->ParseDXLToBucketsArray())).Get()));
+		CDouble dDiffNDVJoin(fabs((dNDVBucketsJoin - CStatisticsUtils::GetNumDistinct(join_histogram->GetBuckets())).Get()));
 		CDouble dDiffNDVRemainJoin(fabs((dNDVRemainJoin - join_histogram->GetDistinctRemain()).Get()));
 		CDouble dDiffFreqRemainJoin(fabs((dFreqRemainJoin - join_histogram->GetFreqRemain()).Get()));
 
-		if (join_histogram->Buckets() != ulBucketsJoin || (dDiffNDVJoin > CStatistics::Epsilon)
+		if (join_histogram->GetNumBuckets() != ulBucketsJoin || (dDiffNDVJoin > CStatistics::Epsilon)
 			|| (dDiffNDVRemainJoin > CStatistics::Epsilon) || (dDiffFreqRemainJoin > CStatistics::Epsilon))
 		{
 			eres = GPOS_FAILED;