greenplumn IMDColStats 源码
greenplumn IMDColStats 代码
文件路径：/src/backend/gporca/libnaucrates/include/naucrates/md/IMDColStats.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2012 EMC Corp.
//
// @filename:
// IMDColStats.h
//
// @doc:
// Interface for column stats
//---------------------------------------------------------------------------
#ifndef GPMD_IMDColStats_H
#define GPMD_IMDColStats_H
#include "gpos/base.h"
#include "naucrates/md/CDXLBucket.h"
#include "naucrates/md/IMDCacheObject.h"
namespace gpmd
{
using namespace gpos;
using namespace gpdxl;
//---------------------------------------------------------------------------
// @class:
// IMDColStats
//
// @doc:
// Interface for column stats
//
//---------------------------------------------------------------------------
class IMDColStats : public IMDCacheObject
{
public:
// object type
Emdtype
MDType() const override
{
return EmdtColStats;
}
// number of buckets
virtual ULONG Buckets() const = 0;
// width
virtual CDouble Width() const = 0;
// null fraction
virtual CDouble GetNullFreq() const = 0;
// ndistinct of remaining tuples
virtual CDouble GetDistinctRemain() const = 0;
// frequency of remaining tuples
virtual CDouble GetFreqRemain() const = 0;
// is the columns statistics missing in the database
virtual BOOL IsColStatsMissing() const = 0;
// get the bucket at the given position
virtual const CDXLBucket *GetDXLBucketAt(ULONG ul) const = 0;
};
} // namespace gpmd
#endif // !GPMD_IMDColStats_H
// EOF
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