greenplumn CXformSubqJoin2Apply 源码
greenplumn CXformSubqJoin2Apply 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/xforms/CXformSubqJoin2Apply.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2011 EMC Corp.
//
// @filename:
// CXformSubqJoin2Apply.h
//
// @doc:
// Transform Inner Join to Apply
//---------------------------------------------------------------------------
#ifndef GPOPT_CXformSubqJoin2Apply_H
#define GPOPT_CXformSubqJoin2Apply_H
#include "gpos/base.h"
#include "gpopt/xforms/CXformSubqueryUnnest.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CXformSubqJoin2Apply
//
// @doc:
// Transform Inner Join with subq to Apply
//
//---------------------------------------------------------------------------
class CXformSubqJoin2Apply : public CXformSubqueryUnnest
{
private:
// hash map between expression and a column reference
using ExprToColRefMap =
CHashMap<CExpression, CColRef, HashPtr<CExpression>,
EqualPtr<CExpression>, CleanupRelease<CExpression>,
CleanupNULL<CColRef>>;
// helper to transform function
void Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *pexpr,
BOOL fEnforceCorrelatedApply) const override;
// collect subqueries that exclusively use outer/inner child
static void CollectSubqueries(CMemoryPool *mp, CExpression *pexpr,
CColRefSetArray *pdrgpcrs,
CExpressionArrays *pdrgpdrgpexprSubqs);
// replace subqueries with scalar identifier based on given map
static CExpression *PexprReplaceSubqueries(CMemoryPool *mp,
CExpression *pexprScalar,
ExprToColRefMap *phmexprcr);
// push down subquery below join
static CExpression *PexprSubqueryPushDown(CMemoryPool *mp,
CExpression *pexpr,
BOOL fEnforceCorrelatedApply);
public:
CXformSubqJoin2Apply(const CXformSubqJoin2Apply &) = delete;
// ctor
explicit CXformSubqJoin2Apply(CMemoryPool *mp);
// ctor
explicit CXformSubqJoin2Apply(CExpression *pexprPattern)
: CXformSubqueryUnnest(pexprPattern)
{
}
// dtor
~CXformSubqJoin2Apply() override = default;
// ident accessors
EXformId
Exfid() const override
{
return ExfSubqJoin2Apply;
}
const CHAR *
SzId() const override
{
return "CXformSubqJoin2Apply";
}
// compute xform promise for a given expression handle
EXformPromise Exfp(CExpressionHandle &exprhdl) const override;
}; // class CXformSubqJoin2Apply
} // namespace gpopt
#endif // !GPOPT_CXformSubqJoin2Apply_H
// EOF
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