greenplumn CExpressionFactorizer 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/operators/CExpressionFactorizer.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2014 VMware, Inc. or its affiliates.
/
/ @filename:
/ CExpressionFactorizer.h
/
/ @doc:
/ Utility functions for expression factorization.
/
/ @owner:
/ ,
/
/ @test:
/
/---------------------------------------------------------------------------
#ifndef GPOPT_CExpressionFactorizer_H
#define GPOPT_CExpressionFactorizer_H
#include "gpos/base.h"
#include "gpopt/base/CUtils.h"
#include "gpopt/operators/CExpression.h"
#include "gpopt/operators/COperator.h"
namespace gpopt
{
using namespace gpos;
/ fwd declarations
class ExprMap;
/---------------------------------------------------------------------------
/ @class:
/ CExpressionFactorizer
/
/ @doc:
/ Expression factorization routines.
/
/---------------------------------------------------------------------------
class CExpressionFactorizer
{
private:
/ map expression to a count, used in factorization
using ExprMap =
CHashMap<CExpression, ULONG, CExpression::HashValue, CUtils::Equals,
CleanupRelease<CExpression>, CleanupDelete<ULONG>>;
/ map operators to an array of expression arrays, corresponding to
/ a disjunction of expressions on columns created by that operator
using SourceToArrayPosMap =
CHashMap<ULONG, CExpressionArrays, gpos::HashValue<ULONG>,
gpos::Equals<ULONG>, CleanupDelete<ULONG>,
CleanupRelease<CExpressionArrays>>;
/ iterator for map of operator to disjunctive form representation
using SourceToArrayPosMapIter =
CHashMapIter<ULONG, CExpressionArrays, gpos::HashValue<ULONG>,
gpos::Equals<ULONG>, CleanupDelete<ULONG>,
CleanupRelease<CExpressionArrays>>;
/ map columns to an array of expression arrays, corresponding to
/ a disjunction of expressions using that column
using ColumnToArrayPosMap =
CHashMap<CColRef, CExpressionArrays, gpos::HashPtr<CColRef>,
gpos::EqualPtr<CColRef>, CleanupNULL<CColRef>,
CleanupRelease<CExpressionArrays>>;
/ iterator for map of column to disjunctive form representation
using ColumnToArrayPosMapIter =
CHashMapIter<CColRef, CExpressionArrays, gpos::HashPtr<CColRef>,
gpos::EqualPtr<CColRef>, CleanupNULL<CColRef>,
CleanupRelease<CExpressionArrays>>;
using PexprProcessDisj = CExpression *(*) (CMemoryPool *, CExpression *,
CExpression *);
/ helper for determining if given expression factor should be added to factors array
static void AddFactor(CMemoryPool *mp, CExpression *pexpr,
CExpressionArray *pdrgpexprFactors,
CExpressionArray *pdrgpexprResidual,
ExprMap *pexprmap, ULONG ulDisjuncts);
/ helper for building a factors map
static ExprMap *PexprmapFactors(CMemoryPool *mp, CExpression *pexpr);
/ factorize common expressions in Or tree
static CExpression *PexprFactorizeDisj(
CMemoryPool *mp, CExpression *pexpr,
CExpression * / pexprLowestLogicalAncestor
);
/ visitor-like function to process descendents that are OR operators
static CExpression *PexprProcessDisjDescendents(
CMemoryPool *mp, CExpression *pexpr,
CExpression *pexprLowestLogicalAncestor, PexprProcessDisj pexprorfun);
/ discover common factors in scalar expression
static CExpression *PexprDiscoverFactors(CMemoryPool *mp,
CExpression *pexpr);
/ if the given expression is a non volatile scalar expression using table
/ columns created by the same operator
/ return true and set ulOpSourceId to the id of the operator that created
/ that column,
/ or if the given expression is a non volatile scalar expression using
/ only one computed column
/ return true and set ppcrComputedColumn to that computed column,
/ otherwise return false
static BOOL FOpSourceIdOrComputedColumn(CExpression *pexpr,
ULONG *ulOpSourceId,
CColRef **ppcrComputedColumn);
/ if the given expression is a scalar that can be pushed, it returns
/ the set of used columns
static CColRefSet *PcrsUsedByPushableScalar(CExpression *pexpr);
/ find the array of expression arrays corresponding to the given
/ operator source id in the given source to array position map
/ or construct a new array and add it to the map
static CExpressionArrays *PdrgPdrgpexprDisjunctArrayForSourceId(
CMemoryPool *mp, SourceToArrayPosMap *psrc2array, BOOL fAllowNewSources,
ULONG ulOpSourceId);
/ find the array of expression arrays corresponding to the given
/ column in the given column to array position map
/ or construct a new array and add it to the map
static CExpressionArrays *PdrgPdrgpexprDisjunctArrayForColumn(
CMemoryPool *mp, ColumnToArrayPosMap *pcol2array, BOOL fAllowNewSources,
CColRef *colref);
/ if the given expression is a table column to constant comparison,
/ record it in the map
static void StoreBaseOpToColumnExpr(
CMemoryPool *mp, CExpression *pexpr, SourceToArrayPosMap *psrc2array,
ColumnToArrayPosMap *pcol2array,
const CColRefSet *pcrsProducedByChildren, BOOL fAllowNewSources,
ULONG ulPosition);
/ construct a filter based on the expressions from 'pdrgpdrgpexpr'
/ and add to the array 'pdrgpexprPrefilters'
static void AddInferredFiltersFromArray(
CMemoryPool *mp, const CExpressionArrays *pdrgpdrgpexpr,
ULONG ulDisjChildrenLength, CExpressionArray *pdrgpexprPrefilters);
/ create a conjunction of the given expression and inferred filters constructed out
/ of the given maps
static CExpression *PexprAddInferredFilters(
CMemoryPool *mp, CExpression *pexpr, SourceToArrayPosMap *psrc2array,
ColumnToArrayPosMap *pcol2array);
/ returns the set of columns produced by the scalar children of the given
/ expression
static CColRefSet *PcrsColumnsProducedByChildren(CMemoryPool *mp,
CExpression *pexpr);
/ compute disjunctive pre-filters that can be pushed to the column creators
static CExpression *PexprExtractInferredFiltersFromDisj(
CMemoryPool *mp, CExpression *pexpr,
CExpression *pexprLowestLogicalAncestor);
public:
/ factorize common expressions
static CExpression *PexprFactorize(CMemoryPool *mp, CExpression *pexpr);
/ compute disjunctive pre-filters that can be pushed to the column creators
static CExpression *PexprExtractInferredFilters(CMemoryPool *mp,
CExpression *pexpr);
};
} / namespace gpopt
#endif / ! GPOPT_CExpressionFactorizer_H
/ EOF
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