greenplumn CLogicalNAryJoin 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/operators/CLogicalNAryJoin.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CLogicalNAryJoin.h
/
/ @doc:
/ N-ary inner join operator
/---------------------------------------------------------------------------
#ifndef GPOS_CLogicalNAryJoin_H
#define GPOS_CLogicalNAryJoin_H
#include "gpos/base.h"
#include "gpopt/operators/CLogicalJoin.h"
namespace gpopt
{
/---------------------------------------------------------------------------
/ @class:
/ CLogicalNAryJoin
/
/ @doc:
/ N-ary inner join operator
/
/---------------------------------------------------------------------------
class CLogicalNAryJoin : public CLogicalJoin
{
private:
/ Indexes that help to find ON predicates for LOJs.
/ If all joins in this NAry join are inner joins, this pointer is NULL and
/ the scalar child of this NAry join contains all join predicates directly.
/ Otherwise, the scalar child is a CScalarNaryJoinPredList and this ULongPtr
/ array has as many entries as there are logical children of the NAry
/ join. For each logical child i, if that child i is part of an inner join
/ or the outer table of an LOJ, then the corresponding entry
/ (*m_lojChildPredIndexes)[i] in this array is 0
/ (GPOPT_ZERO_INNER_JOIN_PRED_INDEX). If the logical child is the right table
/ of an LOJ, the corresponding index indicates the child index of the
/ CScalarNAryJoinPredList expression that contains the ON predicate for the
/ LOJ.
ULongPtrArray *m_lojChildPredIndexes;
public:
CLogicalNAryJoin(const CLogicalNAryJoin &) = delete;
/ ctor
explicit CLogicalNAryJoin(CMemoryPool *mp);
CLogicalNAryJoin(CMemoryPool *mp, ULongPtrArray *lojChildIndexes);
/ dtor
~CLogicalNAryJoin() override
{
CRefCount::SafeRelease(m_lojChildPredIndexes);
}
/ ident accessors
EOperatorId
Eopid() const override
{
return EopLogicalNAryJoin;
}
/ return a string for operator name
const CHAR *
SzId() const override
{
return "CLogicalNAryJoin";
}
/-------------------------------------------------------------------------------------
/ Derived Relational Properties
/-------------------------------------------------------------------------------------
/ derive not nullable columns
CColRefSet *DeriveNotNullColumns(CMemoryPool *mp,
CExpressionHandle &exprhdl) const override;
/ derive max card
CMaxCard DeriveMaxCard(CMemoryPool *mp,
CExpressionHandle &exprhdl) const override;
/ derive constraint property
CPropConstraint *DerivePropertyConstraint(
CMemoryPool *mp, CExpressionHandle &exprhdl) const override;
/-------------------------------------------------------------------------------------
/ Derived Stats
/-------------------------------------------------------------------------------------
/ promise level for stat derivation
EStatPromise
Esp(CExpressionHandle & / exprhdl
) const override
{
/ we should use the expanded join order for stat derivation
return EspLow;
}
/-------------------------------------------------------------------------------------
/ Transformations
/-------------------------------------------------------------------------------------
/ candidate set of xforms
CXformSet *PxfsCandidates(CMemoryPool *mp) const override;
/-------------------------------------------------------------------------------------
/-------------------------------------------------------------------------------------
/-------------------------------------------------------------------------------------
/ conversion function
static CLogicalNAryJoin *
PopConvert(COperator *pop)
{
GPOS_ASSERT(nullptr != pop);
return dynamic_cast<CLogicalNAryJoin *>(pop);
}
/ conversion function, only if the NAryJoin has LOJ children
static CLogicalNAryJoin *PopConvertNAryLOJ(COperator *pop);
BOOL
HasOuterJoinChildren() const
{
return (nullptr != m_lojChildPredIndexes);
}
BOOL
IsInnerJoinChild(ULONG child_num) const
{
return (nullptr == m_lojChildPredIndexes ||
*((*m_lojChildPredIndexes)[child_num]) == 0);
}
ULongPtrArray *
GetLojChildPredIndexes() const
{
return m_lojChildPredIndexes;
}
CExpression *
GetInnerJoinPreds(CExpression *nary_join_expr) const
{
GPOS_ASSERT(nary_join_expr->Pop() == this);
if (HasOuterJoinChildren())
{
/ return the first child of CScalarNAryJoinPredList
return (*((*nary_join_expr)[nary_join_expr->Arity() - 1]))[0];
}
return (*nary_join_expr)[nary_join_expr->Arity() - 1];
}
CExpression *
GetOnPredicateForLOJChild(CExpression *nary_join_expr,
ULONG child_num) const
{
GPOS_ASSERT(nary_join_expr->Pop() == this);
GPOS_ASSERT(0 < *(*m_lojChildPredIndexes)[child_num]);
/ m_lojChildPredIndexes stores the index in the child of the scalar argument
/ (a CScalarNAryJoinPredList) that has our ON predicate
/ |------ the scalar child of the NAry join ------| |- grandchild corresponding to LOJ-|
return (*((*nary_join_expr)[nary_join_expr->Arity() - 1]))[*(
*m_lojChildPredIndexes)[child_num]];
}
/ get the true inner join predicates, excluding predicates that use ColRefs
/ coming from non-inner joins
CExpression *GetTrueInnerJoinPreds(CMemoryPool *mp,
CExpressionHandle &exprhdl) const;
/ given an existing scalar child of an NAry join, make a new copy, replacing
/ only the inner join predicates and leaving the LOJ ON predicates the same
CExpression *ReplaceInnerJoinPredicates(
CMemoryPool *mp, CExpression *old_nary_join_scalar_expr,
CExpression *new_inner_join_preds);
IOstream &OsPrint(IOstream &os) const override;
}; / class CLogicalNAryJoin
} / namespace gpopt
#endif / !GPOS_CLogicalNAryJoin_H
/ EOF
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