greenplumn CPhysicalLimit 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/operators/CPhysicalLimit.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CPhysicalLimit.h
/
/ @doc:
/ Physical Limit operator
/---------------------------------------------------------------------------
#ifndef GPOPT_CPhysicalLimit_H
#define GPOPT_CPhysicalLimit_H
#include "gpos/base.h"
#include "gpopt/base/COrderSpec.h"
#include "gpopt/operators/CPhysical.h"
namespace gpopt
{
/---------------------------------------------------------------------------
/ @class:
/ CPhysicalLimit
/
/ @doc:
/ Limit operator
/
/---------------------------------------------------------------------------
class CPhysicalLimit : public CPhysical
{
private:
/ order spec
COrderSpec *m_pos;
/ global limit
BOOL m_fGlobal;
/ does limit specify a number of rows?
BOOL m_fHasCount;
/ this is a top limit right under a DML or CTAS operation
BOOL m_top_limit_under_dml;
/ columns used by order spec
CColRefSet *m_pcrsSort;
public:
CPhysicalLimit(const CPhysicalLimit &) = delete;
/ ctor
CPhysicalLimit(CMemoryPool *mp, COrderSpec *pos, BOOL fGlobal,
BOOL fHasCount, BOOL fTopLimitUnderDML);
/ dtor
~CPhysicalLimit() override;
/ ident accessors
EOperatorId
Eopid() const override
{
return EopPhysicalLimit;
}
const CHAR *
SzId() const override
{
return "CPhysicalLimit";
}
/ hash function
ULONG
HashValue() const override
{
return gpos::CombineHashes(
gpos::CombineHashes(COperator::HashValue(), m_pos->HashValue()),
gpos::CombineHashes(gpos::HashValue<BOOL>(&m_fGlobal),
gpos::HashValue<BOOL>(&m_fHasCount)));
}
/ order spec
COrderSpec *
Pos() const
{
return m_pos;
}
/ global limit
BOOL
FGlobal() const
{
return m_fGlobal;
}
/ does limit specify a number of rows
BOOL
FHasCount() const
{
return m_fHasCount;
}
/ must the limit be always kept
BOOL
IsTopLimitUnderDMLorCTAS() const
{
return m_top_limit_under_dml;
}
/ match function
BOOL Matches(COperator *) const override;
/ sensitivity to order of inputs
BOOL
FInputOrderSensitive() const override
{
return true;
}
/-------------------------------------------------------------------------------------
/ Required Plan Properties
/-------------------------------------------------------------------------------------
/ compute required output columns of the n-th child
CColRefSet *PcrsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
CColRefSet *pcrsRequired, ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) override;
/ compute required ctes of the n-th child
CCTEReq *PcteRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
CCTEReq *pcter, ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) const override;
/ compute required sort order of the n-th child
COrderSpec *PosRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
COrderSpec *posRequired, ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) const override;
/ compute required distribution of the n-th child
CDistributionSpec *PdsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
CDistributionSpec *pdsRequired,
ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) const override;
/ compute required rewindability of the n-th child
CRewindabilitySpec *PrsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
CRewindabilitySpec *prsRequired,
ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) const override;
/ check if required columns are included in output columns
BOOL FProvidesReqdCols(CExpressionHandle &exprhdl, CColRefSet *pcrsRequired,
ULONG ulOptReq) const override;
/-------------------------------------------------------------------------------------
/ Derived Plan Properties
/-------------------------------------------------------------------------------------
/ derive sort order
COrderSpec *PosDerive(CMemoryPool *mp,
CExpressionHandle &exprhdl) const override;
/ derive distribution
CDistributionSpec *PdsDerive(CMemoryPool *mp,
CExpressionHandle &exprhdl) const override;
/ derive rewindability
CRewindabilitySpec *PrsDerive(CMemoryPool *mp,
CExpressionHandle &exprhdl) const override;
/-------------------------------------------------------------------------------------
/ Enforced Properties
/-------------------------------------------------------------------------------------
/ return order property enforcing type for this operator
CEnfdProp::EPropEnforcingType EpetOrder(
CExpressionHandle &exprhdl, const CEnfdOrder *peo) const override;
/ return distribution property enforcing type for this operator
CEnfdProp::EPropEnforcingType EpetDistribution(
CExpressionHandle &exprhdl,
const CEnfdDistribution *ped) const override;
/ return rewindability property enforcing type for this operator
CEnfdProp::EPropEnforcingType EpetRewindability(
CExpressionHandle &, / exprhdl
const CEnfdRewindability * / per
) const override;
/ return true if operator passes through stats obtained from children,
/ this is used when computing stats during costing
BOOL
FPassThruStats() const override
{
return false;
}
/-------------------------------------------------------------------------------------
/-------------------------------------------------------------------------------------
/-------------------------------------------------------------------------------------
/ print
IOstream &OsPrint(IOstream &) const override;
/ conversion function
static CPhysicalLimit *
PopConvert(COperator *pop)
{
GPOS_ASSERT(nullptr != pop);
GPOS_ASSERT(EopPhysicalLimit == pop->Eopid());
return dynamic_cast<CPhysicalLimit *>(pop);
}
CEnfdDistribution *Ped(CMemoryPool *mp, CExpressionHandle &exprhdl,
CReqdPropPlan *prppInput, ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulDistrReq) override;
}; / class CPhysicalLimit
} / namespace gpopt
#endif / !GPOPT_CPhysicalLimit_H
/ EOF
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