//---------------------------------------------------------------------------
// @function:
// CXformCollapseGbAgg::Transform
//
// @doc:
// Actual transformation to collapse two cascaded group by operators;
// if the top Gb grouping columns are subset of bottom Gb grouping
// columns AND both Gb operators do not define agg functions, we can
// remove the bottom group by operator
//
//
//---------------------------------------------------------------------------
void
CXformCollapseGbAgg::Transform
(
CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr
)
const
{
GPOS_ASSERT(NULL != pxfctxt);
GPOS_ASSERT(NULL != pxfres);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
IMemoryPool *pmp = pxfctxt->Pmp();
// extract components
CLogicalGbAgg *popTopGbAgg = CLogicalGbAgg::PopConvert(pexpr->Pop());
GPOS_ASSERT(0 < popTopGbAgg->Pdrgpcr()->UlLength());
GPOS_ASSERT(popTopGbAgg->FGlobal());
CExpression *pexprRelational = (*pexpr)[0];
CExpression *pexprTopProjectList = (*pexpr)[1];
CLogicalGbAgg *popBottomGbAgg = CLogicalGbAgg::PopConvert(pexprRelational->Pop());
CExpression *pexprChild = (*pexprRelational)[0];
CExpression *pexprBottomProjectList = (*pexprRelational)[1];
if (!popBottomGbAgg->FGlobal())
{
// bottom GbAgg must be global to prevent xform from getting applied to splitted GbAggs
return;
}
if (0 < pexprTopProjectList->UlArity() || 0 < pexprBottomProjectList->UlArity())
{
// exit if any of the Gb operators has an aggregate function
return;
}
#ifdef GPOS_DEBUG
// for two cascaded GbAgg ops with no agg functions, top grouping
// columns must be a subset of bottom grouping columns
CColRefSet *pcrsTopGrpCols = GPOS_NEW(pmp) CColRefSet(pmp, popTopGbAgg->Pdrgpcr());
CColRefSet *pcrsBottomGrpCols = GPOS_NEW(pmp) CColRefSet(pmp, popBottomGbAgg->Pdrgpcr());
GPOS_ASSERT(pcrsBottomGrpCols->FSubset(pcrsTopGrpCols));
pcrsTopGrpCols->Release();
pcrsBottomGrpCols->Release();
#endif // GPOS_DEBUG
pexprChild->AddRef();
CExpression *pexprSelect = CUtils::PexprLogicalSelect(pmp, pexprChild, CPredicateUtils::PexprConjunction(pmp, NULL /*pdrgpexpr*/));
popTopGbAgg->AddRef();
pexprTopProjectList->AddRef();
CExpression *pexprGbAggNew = GPOS_NEW(pmp) CExpression(pmp, popTopGbAgg, pexprSelect, pexprTopProjectList);
pxfres->Add(pexprGbAggNew);
}
//---------------------------------------------------------------------------
// @function:
// CXformPushGbWithHavingBelowJoin::Transform
//
// @doc:
// Actual transformation
//
//---------------------------------------------------------------------------
void
CXformPushGbWithHavingBelowJoin::Transform
(
CXformContext *pxfctxt,
CXformResult *pxfres,
CExpression *pexpr
)
const
{
GPOS_ASSERT(NULL != pxfctxt);
GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr));
GPOS_ASSERT(FCheckPattern(pexpr));
IMemoryPool *mp = pxfctxt->Pmp();
CExpression *pexprGb = (*pexpr)[0];
CLogicalGbAgg *popGbAgg = CLogicalGbAgg::PopConvert(pexprGb->Pop());
if (!popGbAgg->FGlobal())
{
// xform only applies to global aggs
return;
}
CExpression *pexprResult = CXformUtils::PexprPushGbBelowJoin(mp, pexpr);
if (NULL != pexprResult)
{
// add alternative to results
pxfres->Add(pexprResult);
}
}
//---------------------------------------------------------------------------
// @function:
// CXformCollapseGbAgg::Exfp
//
// @doc:
// Compute xform promise for a given expression handle;
// GbAgg must be global and have non empty grouping columns
//
//---------------------------------------------------------------------------
CXform::EXformPromise
CXformCollapseGbAgg::Exfp
(
CExpressionHandle &exprhdl
)
const
{
CLogicalGbAgg *popAgg = CLogicalGbAgg::PopConvert(exprhdl.Pop());
if (!popAgg->FGlobal() || 0 == popAgg->Pdrgpcr()->UlLength())
{
return CXform::ExfpNone;
}
return CXform::ExfpHigh;
}
//---------------------------------------------------------------------------
// @function:
// CXformPushGbBelowJoin::Exfp
//
// @doc:
// Compute xform promise for a given expression handle;
// we only push down global aggregates
//
//---------------------------------------------------------------------------
CXform::EXformPromise
CXformPushGbBelowJoin::Exfp
(
CExpressionHandle &exprhdl
)
const
{
CLogicalGbAgg *popGbAgg = CLogicalGbAgg::PopConvert(exprhdl.Pop());
if (!popGbAgg->FGlobal())
{
return CXform::ExfpNone;
}
return CXform::ExfpHigh;
}
//---------------------------------------------------------------------------
// @function:
// CXformGbAgg2Apply::Exfp
//
// @doc:
// Compute xform promise for a given expression handle;
// scalar child must have subquery
//
//---------------------------------------------------------------------------
CXform::EXformPromise
CXformGbAgg2Apply::Exfp
(
CExpressionHandle &exprhdl
)
const
{
CLogicalGbAgg *popGbAgg = CLogicalGbAgg::PopConvert(exprhdl.Pop());
if (popGbAgg->FGlobal() && exprhdl.Pdpscalar(1)->FHasSubquery())
{
return CXform::ExfpHigh;
}
return CXform::ExfpNone;
}
