greenplumn CXformJoinAssociativity 源码
greenplumn CXformJoinAssociativity 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformJoinAssociativity.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2011 EMC Corp.
//
// @filename:
// CXformJoinAssociativity.h
//
// @doc:
// Transform left-deep join tree by associativity
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformJoinAssociativity_H
#define GPOPT_CXformJoinAssociativity_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformExploration.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformJoinAssociativity
//
// @doc:
// Associative transformation of left-deep join tree
//
//---------------------------------------------------------------------------
class CXformJoinAssociativity : public CXformExploration
{
private:
// helper function for creating the new join predicate
static void CreatePredicates(CMemoryPool *mp, CExpression *pexpr,
CExpressionArray *pdrgpexprLower,
CExpressionArray *pdrgpexprUpper);
public:
CXformJoinAssociativity(const CXformJoinAssociativity &) = delete;
// ctor
explicit CXformJoinAssociativity(CMemoryPool *mp);
// dtor
~CXformJoinAssociativity() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfJoinAssociativity;
}
// return a string for xform name
const CHAR *
SzId() const override
{
return "CXformJoinAssociativity";
}
// compute xform promise for a given expression handle
EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
// actual transform
void Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *pexpr) const override;
}; // class CXformJoinAssociativity
} // namespace gpopt
#endif // !GPOPT_CXformJoinAssociativity_H
// EOF
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