greenplumn CXformExploration 源码
greenplumn CXformExploration 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformExploration.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2011 EMC Corp.
//
// @filename:
// CXformExploration.h
//
// @doc:
// Base class for exploration transforms
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformExploration_H
#define GPOPT_CXformExploration_H
#include "gpos/base.h"
#include "gpopt/xforms/CXform.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformExploration
//
// @doc:
// Base class for all explorations
//
//---------------------------------------------------------------------------
class CXformExploration : public CXform
{
private:
public:
CXformExploration(const CXformExploration &) = delete;
// ctor
explicit CXformExploration(CExpression *pexpr);
// dtor
~CXformExploration() override;
// type of operator
BOOL
FExploration() const override
{
GPOS_ASSERT(!FSubstitution() && !FImplementation());
return true;
}
// is transformation a subquery unnesting (Subquery To Apply) xform?
virtual BOOL
FSubqueryUnnesting() const
{
return false;
}
// is transformation an Apply decorrelation (Apply To Join) xform?
virtual BOOL
FApplyDecorrelating() const
{
return false;
}
// do stats need to be computed before applying xform?
virtual BOOL
FNeedsStats() const
{
return false;
}
// conversion function
static CXformExploration *
Pxformexp(CXform *pxform)
{
GPOS_ASSERT(nullptr != pxform);
GPOS_ASSERT(pxform->FExploration());
return dynamic_cast<CXformExploration *>(pxform);
}
}; // class CXformExploration
} // namespace gpopt
#endif // !GPOPT_CXformExploration_H
// EOF
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