greenplumn CUnionAllStatsProcessor 源码

greenplumn CUnionAllStatsProcessor 代码

文件路径：/src/backend/gporca/libnaucrates/src/statistics/CUnionAllStatsProcessor.cpp

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright 2018 VMware, Inc. or its affiliates.
//
//	@filename:
//		CUnionAllStatsProcessor.cpp
//
//	@doc:
//		Statistics helper routines for processing union all operations
//---------------------------------------------------------------------------

#include "naucrates/statistics/CUnionAllStatsProcessor.h"

#include "gpopt/base/COptCtxt.h"
#include "naucrates/statistics/CStatisticsUtils.h"

using namespace gpopt;

// return statistics object after union all operation with input statistics object
CStatistics *
CUnionAllStatsProcessor::CreateStatsForUnionAll(
	CMemoryPool *mp, const CStatistics *stats_first_child,
	const CStatistics *stats_second_child, ULongPtrArray *output_colids,
	ULongPtrArray *first_child_colids, ULongPtrArray *second_child_colids)
{
	GPOS_ASSERT(nullptr != mp);
	GPOS_ASSERT(nullptr != stats_second_child);

	// lengths must match
	GPOS_ASSERT(output_colids->Size() == first_child_colids->Size());
	GPOS_ASSERT(output_colids->Size() == second_child_colids->Size());

	// create hash map from colid -> histogram for resultant structure
	UlongToHistogramMap *histograms_new = GPOS_NEW(mp) UlongToHistogramMap(mp);

	// column ids on which widths are to be computed
	UlongToDoubleMap *column_to_width_map = GPOS_NEW(mp) UlongToDoubleMap(mp);

	BOOL is_empty_unionall =
		stats_first_child->IsEmpty() && stats_second_child->IsEmpty();
	CColumnFactory *col_factory = COptCtxt::PoctxtFromTLS()->Pcf();
	CDouble unionall_rows = CStatistics::MinRows;
	if (is_empty_unionall)
	{
		CHistogram::AddDummyHistogramAndWidthInfo(
			mp, col_factory, histograms_new, column_to_width_map, output_colids,
			true /*is_empty*/);
	}
	else
	{
		const ULONG len = output_colids->Size();
		for (ULONG ul = 0; ul < len; ul++)
		{
			ULONG output_colid = *(*output_colids)[ul];
			ULONG first_child_colid = *(*first_child_colids)[ul];
			ULONG second_child_colid = *(*second_child_colids)[ul];

			const CHistogram *first_child_histogram =
				stats_first_child->GetHistogram(first_child_colid);
			GPOS_ASSERT(nullptr != first_child_histogram);
			const CHistogram *second_child_histogram =
				stats_second_child->GetHistogram(second_child_colid);
			GPOS_ASSERT(nullptr != second_child_histogram);

			if (first_child_histogram->IsWellDefined() ||
				second_child_histogram->IsWellDefined())
			{
				CHistogram *output_histogram =
					first_child_histogram->MakeUnionAllHistogramNormalize(
						stats_first_child->Rows(), second_child_histogram,
						stats_second_child->Rows());
				CStatisticsUtils::AddHistogram(
					mp, output_colid, output_histogram, histograms_new);
				GPOS_DELETE(output_histogram);
			}
			else
			{
				CColRef *column_ref = col_factory->LookupColRef(output_colid);
				GPOS_ASSERT(nullptr != column_ref);

				CHistogram *dummy_histogram = CHistogram::MakeDefaultHistogram(
					mp, column_ref, false /* is_empty*/);
				histograms_new->Insert(GPOS_NEW(mp) ULONG(output_colid),
									   dummy_histogram);
			}

			// look up width
			const CDouble *col_width =
				stats_first_child->GetWidth(first_child_colid);
			GPOS_ASSERT(nullptr != col_width);
			column_to_width_map->Insert(GPOS_NEW(mp) ULONG(output_colid),
										GPOS_NEW(mp) CDouble(*col_width));
		}

		unionall_rows = stats_first_child->Rows() + stats_second_child->Rows();
	}

	// release inputs
	output_colids->Release();
	first_child_colids->Release();
	second_child_colids->Release();

	// create an output stats object
	CStatistics *unionall_stats = GPOS_NEW(mp)
		CStatistics(mp, histograms_new, column_to_width_map, unionall_rows,
					is_empty_unionall, 0 /* m_num_predicates */
		);

	// In the output statistics object, the upper bound source cardinality of the UNION ALL column
	// is the estimate union all cardinality.

	// modify upper bound card information
	CStatisticsUtils::ComputeCardUpperBounds(
		mp, stats_first_child, unionall_stats, unionall_rows,
		CStatistics::EcbmOutputCard /* card_bounding_method */);

	return unionall_stats;
}

// EOF

相关信息

greenplumn 源码目录

相关文章

greenplumn CBucket 源码

greenplumn CFilterStatsProcessor 源码

greenplumn CGroupByStatsProcessor 源码

greenplumn CHistogram 源码

greenplumn CInnerJoinStatsProcessor 源码

greenplumn CJoinStatsProcessor 源码

greenplumn CLeftAntiSemiJoinStatsProcessor 源码

greenplumn CLeftOuterJoinStatsProcessor 源码

greenplumn CLeftSemiJoinStatsProcessor 源码

greenplumn CLimitStatsProcessor 源码