greenplumn CXformEagerAgg 源码
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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