greenplumn CXformEagerAgg 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformEagerAgg.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2018 VMware, Inc. or its affiliates.
/
/ @filename:
/ CXformEagerAgg.h
/
/ @doc:
/ Eagerly push aggregates below join when there is no primary/foreign keys
/---------------------------------------------------------------------------
#ifndef GPOPT_CXformEagerAgg_H
#define GPOPT_CXformEagerAgg_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
/---------------------------------------------------------------------------
/ @class:
/ CXformEagerAgg
/
/ @doc:
/ Eagerly push aggregates below join
/
/---------------------------------------------------------------------------
class CXformEagerAgg : public CXformExploration
{
public:
CXformEagerAgg(const CXformEagerAgg &) = delete;
/ ctor
explicit CXformEagerAgg(CMemoryPool *mp);
/ ctor
explicit CXformEagerAgg(CExpression *exprPattern);
/ dtor
~CXformEagerAgg() override = default;
/ ident accessors
EXformId
Exfid() const override
{
return ExfEagerAgg;
}
const CHAR *
SzId() const override
{
return "CXformEagerAgg";
}
/ compatibility function for eager aggregation
BOOL
FCompatible(CXform::EXformId exfid) override
{
return (CXform::ExfEagerAgg != exfid) &&
(CXform::ExfSplitGbAgg != exfid) &&
(CXform::ExfSplitDQA != exfid);
}
/ compute xform promise for a given expression handle
EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
/ actual transform
void Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *expr) const override;
/ return true if xform should be applied only once
BOOL
IsApplyOnce() override
{
return true;
};
private:
/ check if transform can be applied
static BOOL CanApplyTransform(CExpression *agg_expr);
/ is this aggregate supported for push down?
static BOOL CanPushAggBelowJoin(CExpression *scalar_agg_func_expr);
/ generate project lists for the lower and upper aggregates
/ from all the original aggregates
static void PopulateLowerUpperProjectList(
CMemoryPool *mp, / memory pool
CExpression *orig_proj_list, / project list of the original aggregate
CExpression *
*lower_proj_list, / output project list of the new lower aggregate
CExpression *
*upper_proj_list / output project list of the new upper aggregate
);
/ generate project element for lower aggregate for a single original aggregate
static void PopulateLowerProjectElement(
CMemoryPool *mp, / memory pool
IMDId *agg_mdid, / original global aggregate function
CWStringConst *agg_name, CExpressionArray *agg_arg_array,
BOOL is_distinct,
CExpression **lower_proj_elem_expr / output project element of the new
/ lower aggregate
);
/ generate project element for upper aggregate
static void PopulateUpperProjectElement(
CMemoryPool *mp, / memory pool
IMDId *agg_mdid, / aggregate mdid to create
CWStringConst *agg_name, CColRef *lower_colref, CColRef *output_colref,
BOOL is_distinct,
CExpression **upper_proj_elem_expr / output project element of the new
/ upper aggregate
);
}; / class CXformEagerAgg
} / namespace gpopt
#endif / !GPOPT_CXformEagerAgg_H
/ EOF
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