greenplumn CEnfdProp 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CEnfdProp.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CEnfdProp.h
/
/ @doc:
/ Base class for all enforceable properties
/---------------------------------------------------------------------------
#ifndef GPOPT_CEnfdProp_H
#define GPOPT_CEnfdProp_H
#include "gpos/base.h"
#include "gpos/common/CDynamicPtrArray.h"
#include "gpos/common/CRefCount.h"
#include "gpopt/base/CPropSpec.h"
#include "gpopt/operators/COperator.h"
namespace gpopt
{
using namespace gpos;
/ prototypes
class CPhysical;
class CReqdPropPlan;
/---------------------------------------------------------------------------
/ @class:
/ CEnfdProp
/
/ @doc:
/ Abstract base class for all enforceable properties.
/
/---------------------------------------------------------------------------
class CEnfdProp : public CRefCount, public DbgPrintMixin<CEnfdProp>
{
public:
/ Definition of property enforcing type for a given operator.
/
/ Each enforced property is queried in CEngine::FCheckEnfdProps() to
/ determine if enforcers are required, optional, unnecessary or
/ prohibited over an operator given an optimization context of
/ properties required of it.
/
/ - Required: operator cannot deliver the required properties on its
/ own, e.g., requiring a sort order from a table scan
/
/ - Optional: operator can request the required properties from its children
/ and preserve them, e.g., requiring a sort order from a filter
/
/ - Prohibited: operator prohibits enforcing the required properties on its
/ output, e.g., requiring a sort order on column A from a sort operator that
/ provides sorting on column B
/
/ - Unnecessary: operator already establishes the required properties on its
/ own, e.g., requiring a sort order on column A from a sort operator that
/ provides sorting on column A. If the required property spec is empty, any
/ operator satisfies it so its type falls into this category.
/
/ NB: 'Prohibited' prevents ANY enforcer to be added for the given
/ operator & optimization context, even if one is required by some other
/ enforced property.
enum EPropEnforcingType
{
EpetRequired,
EpetOptional,
EpetProhibited,
EpetUnnecessary,
EpetSentinel
};
private:
public:
CEnfdProp(const CEnfdProp &) = delete;
/ ctor
CEnfdProp() = default;
/ dtor
~CEnfdProp() override = default;
/ append enforcers to dynamic array for the given plan properties
void
AppendEnforcers(
CMemoryPool *mp, CReqdPropPlan *prpp,
CExpressionArray *pdrgpexpr, / array of enforcer expressions
CExpression *pexprChild, / leaf in the target group where
/ enforcers will be added
CEnfdProp::EPropEnforcingType epet, CExpressionHandle &exprhdl) const
{
if (FEnforce(epet))
{
Pps()->AppendEnforcers(mp, exprhdl, prpp, pdrgpexpr, pexprChild);
}
}
/ property spec accessor
virtual CPropSpec *Pps() const = 0;
/ hash function
virtual ULONG HashValue() const = 0;
/ check if operator requires an enforcer under given enforceable property
/ based on the derived enforcing type
static BOOL
FEnforce(EPropEnforcingType epet)
{
return CEnfdProp::EpetOptional == epet ||
CEnfdProp::EpetRequired == epet;
}
/ check if operator requires optimization under given enforceable property
/ based on the derived enforcing type
static BOOL
FOptimize(EPropEnforcingType epet)
{
return CEnfdProp::EpetOptional == epet ||
CEnfdProp::EpetUnnecessary == epet;
}
virtual gpos::IOstream &OsPrint(gpos::IOstream &os) const = 0;
}; / class CEnfdProp
/ shorthand for printing
IOstream &operator<<(IOstream &os, CEnfdProp &efdprop);
} / namespace gpopt
#endif / !GPOPT_CEnfdProp_H
/ EOF
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