greenplumn CXformExpandNAryJoinDP 源码
greenplumn CXformExpandNAryJoinDP 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformExpandNAryJoinDP.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2013 EMC Corp.
//
// @filename:
// CXformExpandNAryJoinDP.h
//
// @doc:
// Expand n-ary join into series of binary joins using dynamic
// programming
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformExpandNAryJoinDP_H
#define GPOPT_CXformExpandNAryJoinDP_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformExpandNAryJoinDP
//
// @doc:
// Expand n-ary join into series of binary joins using dynamic
// programming
//
//---------------------------------------------------------------------------
class CXformExpandNAryJoinDP : public CXformExploration
{
private:
public:
CXformExpandNAryJoinDP(const CXformExpandNAryJoinDP &) = delete;
// ctor
explicit CXformExpandNAryJoinDP(CMemoryPool *mp);
// dtor
~CXformExpandNAryJoinDP() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfExpandNAryJoinDP;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformExpandNAryJoinDP";
}
// compute xform promise for a given expression handle
EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
// do stats need to be computed before applying xform?
BOOL
FNeedsStats() const override
{
return true;
}
// actual transform
void Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *pexpr) const override;
}; // class CXformExpandNAryJoinDP
} // namespace gpopt
#endif // !GPOPT_CXformExpandNAryJoinDP_H
// EOF
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