//---------------------------------------------------------------------------
// @function:
// CXformImplementLimit::Transform
//
// @doc:
// Actual transformation
//
//---------------------------------------------------------------------------
void
CXformImplementLimit::Transform
(
CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr
)
const
{
GPOS_ASSERT(NULL != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
IMemoryPool *pmp = pxfctxt->Pmp();
// extract components
CLogicalLimit *popLimit = CLogicalLimit::PopConvert(pexpr->Pop());
CExpression *pexprRelational = (*pexpr)[0];
CExpression *pexprScalarStart = (*pexpr)[1];
CExpression *pexprScalarRows = (*pexpr)[2];
COrderSpec *pos = popLimit->Pos();
// addref all components
pexprRelational->AddRef();
pexprScalarStart->AddRef();
pexprScalarRows->AddRef();
popLimit->Pos()->AddRef();
// assemble physical operator
CExpression *pexprLimit =
GPOS_NEW(pmp) CExpression
(
pmp,
GPOS_NEW(pmp) CPhysicalLimit
(
pmp,
pos,
popLimit->FGlobal(),
popLimit->FHasCount(),
popLimit->FTopLimitUnderDML()
),
pexprRelational,
pexprScalarStart,
pexprScalarRows
);
// add alternative to results
pxfres->Add(pexprLimit);
}
//---------------------------------------------------------------------------
// @function:
// CLogicalLimit::FMatch
//
// @doc:
// Match function on operator level
//
//---------------------------------------------------------------------------
BOOL
CLogicalLimit::FMatch
(
COperator *pop
)
const
{
if (pop->Eopid() == Eopid())
{
CLogicalLimit *popLimit = CLogicalLimit::PopConvert(pop);
if (popLimit->FGlobal() == m_fGlobal &&
popLimit->FHasCount() == m_fHasCount)
{
// match if order specs match
return m_pos->FMatch(popLimit->m_pos);
}
}
return false;
}