greenplumn CPartialPlan 源码
greenplumn CPartialPlan 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/engine/CPartialPlan.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2014 VMware, Inc. or its affiliates.
//
// @filename:
// CPartialPlan.h
//
// @doc:
//
// A partial plan is a group expression where none (or not all) of its
// optimal child plans are discovered yet,
// by assuming the smallest possible cost of unknown child plans, a partial
// plan's cost gives a lower bound on the cost of the corresponding complete plan,
// this information is used to prune the optimization search space during branch
// and bound search
//---------------------------------------------------------------------------
#ifndef GPOPT_CPartialPlan_H
#define GPOPT_CPartialPlan_H
#include "gpos/base.h"
#include "gpos/common/CRefCount.h"
#include "gpopt/base/CReqdProp.h"
#include "gpopt/cost/ICostModel.h"
namespace gpopt
{
using namespace gpos;
class CGroupExpression;
class CCost;
class CCostContext;
//---------------------------------------------------------------------------
// @class:
// CPartialPlan
//
// @doc:
// Description of partial plans created during optimization
//
//---------------------------------------------------------------------------
class CPartialPlan : public CRefCount
{
private:
// root group expression
CGroupExpression *m_pgexpr;
// required plan properties of root operator
CReqdPropPlan *m_prpp;
// cost context of known child plan -- can be null if no child plans are known
CCostContext *m_pccChild;
// index of known child plan
ULONG m_ulChildIndex;
// extract costing info from children
void ExtractChildrenCostingInfo(CMemoryPool *mp, ICostModel *pcm,
CExpressionHandle &exprhdl,
ICostModel::SCostingInfo *pci);
public:
CPartialPlan(const CPartialPlan &) = delete;
// ctor
CPartialPlan(CGroupExpression *pgexpr, CReqdPropPlan *prpp,
CCostContext *pccChild, ULONG child_index);
// dtor
~CPartialPlan() override;
// group expression accessor
CGroupExpression *
Pgexpr() const
{
return m_pgexpr;
}
// plan properties accessor
CReqdPropPlan *
Prpp() const
{
return m_prpp;
}
// child cost context accessor
CCostContext *
PccChild() const
{
return m_pccChild;
}
// child index accessor
ULONG
UlChildIndex() const
{
return m_ulChildIndex;
}
// compute partial plan cost
CCost CostCompute(CMemoryPool *mp);
// hash function used for cost bounding
static ULONG HashValue(const CPartialPlan *ppp);
// equality function used for for cost bounding
static BOOL Equals(const CPartialPlan *pppFst, const CPartialPlan *pppSnd);
}; // class CPartialPlan
} // namespace gpopt
#endif // !GPOPT_CPartialPlan_H
// EOF
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