greenplumn CColumnDescriptor 源码
greenplumn CColumnDescriptor 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/metadata/CColumnDescriptor.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2009 Greenplum, Inc.
//
// @filename:
// CColumnDescriptor.h
//
// @doc:
// Abstraction of columns in tables, functions, external tables etc.
//---------------------------------------------------------------------------
#ifndef GPOPT_CColumnDescriptor_H
#define GPOPT_CColumnDescriptor_H
#include "gpos/base.h"
#include "gpos/common/CRefCount.h"
#include "gpopt/metadata/CName.h"
#include "naucrates/md/IMDType.h"
namespace gpopt
{
using namespace gpmd;
//---------------------------------------------------------------------------
// @class:
// CColumnDescriptor
//
// @doc:
// Metadata abstraction for columns that exist in the catalog;
// Transient columns as computed during query execution do not have a
// column descriptor;
//
//---------------------------------------------------------------------------
class CColumnDescriptor : public CRefCount,
public DbgPrintMixin<CColumnDescriptor>
{
private:
// type information
const IMDType *m_pmdtype;
// type modifier
const INT m_type_modifier;
// name of column -- owned
CName m_name;
// attribute number
INT m_iAttno;
// does column allow null values?
BOOL m_is_nullable;
// width of the column, for instance char(10) column has width 10
ULONG m_width;
// is the column a distribution col
BOOL m_is_dist_col;
public:
// ctor
CColumnDescriptor(CMemoryPool *mp, const IMDType *pmdtype,
INT type_modifier, const CName &name, INT attno,
BOOL is_nullable, ULONG ulWidth = gpos::ulong_max);
// dtor
~CColumnDescriptor() override;
// return column name
const CName &
Name() const
{
return m_name;
}
// return metadata type
const IMDType *
RetrieveType() const
{
return m_pmdtype;
}
// type modifier
INT
TypeModifier() const
{
return m_type_modifier;
}
// return attribute number
INT
AttrNum() const
{
return m_iAttno;
}
// does column allow null values?
BOOL
IsNullable() const
{
return m_is_nullable;
}
// is this a system column
virtual BOOL
IsSystemColumn() const
{
return (0 > m_iAttno);
}
// width of the column
virtual ULONG
Width() const
{
return m_width;
}
// is this a distribution column
BOOL
IsDistCol() const
{
return m_is_dist_col;
}
// set this column as a distribution column
void
SetAsDistCol()
{
m_is_dist_col = true;
}
IOstream &OsPrint(IOstream &os) const;
}; // class CColumnDescriptor
} // namespace gpopt
#endif // !GPOPT_CColumnDescriptor_H
// EOF
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