greenplumn CQueryContext 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CQueryContext.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CQueryContext.h
/
/ @doc:
/ A container for query-specific input objects to the optimizer
/---------------------------------------------------------------------------
#ifndef GPOPT_CQueryContext_H
#define GPOPT_CQueryContext_H
#include "gpos/base.h"
#include "gpos/common/DbgPrintMixin.h"
#include "gpopt/base/CReqdPropPlan.h"
#include "gpopt/base/CReqdPropRelational.h"
#include "gpopt/operators/CExpressionPreprocessor.h"
#include "gpopt/search/CGroupExpression.h"
namespace gpopt
{
using namespace gpos;
/---------------------------------------------------------------------------
/ @class:
/ CQueryContext
/
/ @doc:
/ Query specific information that optimizer receives as input
/ representing the requirements that need to be satisfied by the final
/ plan. This includes:
/ - Input logical expression
/ - Required columns
/ - Required plan (physical) properties at the top level of the query.
/ This will include sort order, rewindability etc requested by the entire
/ query.
/
/ The function CQueryContext::PqcGenerate() is the main routine that
/ generates a query context object for a given logical expression and
/ required output columns. See there for more details of how
/ CQueryContext is constructed.
/
/ NB: One instance of CQueryContext is created per query. It is then used
/ to initialize the CEngine.
/
/
/---------------------------------------------------------------------------
class CQueryContext : public DbgPrintMixin<CQueryContext>
{
private:
/ required plan properties in optimizer's produced plan
CReqdPropPlan *m_prpp;
/ required array of output columns
CColRefArray *m_pdrgpcr;
/ required system columns, collected from of output columns
CColRefArray *m_pdrgpcrSystemCols;
/ array of output column names
CMDNameArray *m_pdrgpmdname;
/ logical expression tree to be optimized
CExpression *m_pexpr;
/ should statistics derivation take place
BOOL m_fDeriveStats;
/ collect system columns from output columns
void SetSystemCols(CMemoryPool *mp);
/ return top level operator in the given expression
static COperator *PopTop(CExpression *pexpr);
public:
CQueryContext(const CQueryContext &) = delete;
/ ctor
CQueryContext(CMemoryPool *mp, CExpression *pexpr, CReqdPropPlan *prpp,
CColRefArray *colref_array, CMDNameArray *pdrgpmdname,
BOOL fDeriveStats);
/ dtor
virtual ~CQueryContext();
BOOL
FDeriveStats() const
{
return m_fDeriveStats;
}
/ expression accessor
CExpression *
Pexpr() const
{
return m_pexpr;
}
/ required plan properties accessor
CReqdPropPlan *
Prpp() const
{
return m_prpp;
}
/ return the array of output column references
CColRefArray *
PdrgPcr() const
{
return m_pdrgpcr;
}
/ system columns
CColRefArray *
PdrgpcrSystemCols() const
{
return m_pdrgpcrSystemCols;
}
/ return the array of output column names
CMDNameArray *
Pdrgpmdname() const
{
return m_pdrgpmdname;
}
/ generate the query context for the given expression and array of output column ref ids
static CQueryContext *PqcGenerate(
CMemoryPool *mp, / memory pool
CExpression *pexpr, / expression representing the query
ULongPtrArray
*pdrgpulQueryOutputColRefId, / array of output column reference id
CMDNameArray *pdrgpmdname, / array of output column names
BOOL fDeriveStats);
#ifdef GPOS_DEBUG
/ debug print
IOstream &OsPrint(IOstream &) const;
#endif / GPOS_DEBUG
/ walk the expression and add the mapping between computed column
/ and their corresponding used column(s)
static void MapComputedToUsedCols(CColumnFactory *col_factory,
CExpression *pexpr);
}; / class CQueryContext
} / namespace gpopt
#endif / !GPOPT_CQueryContext_H
/ EOF
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