CXform
CXforml类作为所有transformation的基础类，其包含了pattern成员m_pexpr。主要是在exploration和implementation expression流程中使用，主要调用Transform函数。其还包含返回相关xforms的集合函数，比如PbsIndexJoinXforms等。
class CXform : public CRefCount {
private: CExpression *m_pexpr; // pattern
CXform(CXform &); // private copy ctor
public:
explicit CXform(CExpression *pexpr); virtual ~CXform();
CExpression *PexprPattern() const { return m_pexpr; } // accessor
static BOOL FEqualIds(const CHAR *szIdOne, const CHAR *szIdTwo); // equality function over xform ids
virtual EXformId Exfid() const = 0; // ident accessors
virtual const CHAR *SzId() const = 0; // return a string for xform name
// the following functions check xform type
virtual BOOL FSubstitution() const { return false; } // is xform substitution?
virtual BOOL FExploration() const { return false; } // is xform exploration?
virtual BOOL FImplementation() const { return false; } // is xform implementation?
virtual BOOL FCompatible(CXform::EXformId) { return true; } // check compatibility with another xform
// actual transformation
virtual void Transform(CXformContext *pxfctxt, CXformResult *pxfres, CExpression *pexpr) const = 0;
// compute xform promise for a given expression handle
virtual EXformPromise Exfp(CExpressionHandle &exprhdl) const = 0;
// return true if xform should be applied only once.
// for expression of type CPatternTree, in deep trees, the number
// of expressions generated for group expression can be significantly
// large causing the Xform to be applied many times. This can lead to
// significantly long planning time, so such Xform should only be applied once
virtual BOOL IsApplyOnce();
// returns a set containing all xforms related to index join
// caller takes ownership of the returned set
static CBitSet *PbsIndexJoinXforms(CMemoryPool *mp);
// returns a set containing all xforms related to bitmap indexes
// caller takes ownership of the returned set
static CBitSet *PbsBitmapIndexXforms(CMemoryPool *mp);
// returns a set containing all xforms related to heterogeneous indexes
// caller takes ownership of the returned set
static CBitSet *PbsHeterogeneousIndexXforms(CMemoryPool *mp);
// returns a set containing all xforms that generate a plan with a hash join
// caller takes ownership of the returned set
static CBitSet *PbsHashJoinXforms(CMemoryPool *mp);
// returns a set containing xforms to use only the join order as available
// in the query
static CBitSet *PbsJoinOrderInQueryXforms(CMemoryPool *mp);
// returns a set containing xforms to use combination of greedy xforms
// for join order
static CBitSet *PbsJoinOrderOnGreedyXforms(CMemoryPool *mp);
// returns a set containing xforms to use for exhaustive join order
static CBitSet *PbsJoinOrderOnExhaustiveXforms(CMemoryPool *mp);
// returns a set containing xforms to use for exhaustive2 join order
static CBitSet *PbsJoinOrderOnExhaustive2Xforms(CMemoryPool *mp);
}; // class CXformCXformExploration和CXformImplementation
CXformExploration类作为Base class for all explorations，其定义如下所示：
class CXformExploration : public CXform {
private: CXformExploration(const CXformExploration &); // private copy ctor
public:
explicit CXformExploration(CExpression *pexpr); // ctor
virtual ~CXformExploration(); // dtor
virtual BOOL FExploration() const { return true; } // type of operator
// is transformation a subquery unnesting (Subquery To Apply) xform?
virtual BOOL FSubqueryUnnesting() const { return false; }
// is transformation an Apply decorrelation (Apply To Join) xform?
virtual BOOL FApplyDecorrelating() const { return false; }
// do stats need to be computed before applying xform?
virtual BOOL FNeedsStats() const { return false; }
// conversion function
static CXformExploration *Pxformexp(CXform *pxform) {
return dynamic_cast<CXformExploration *>(pxform);
}
}; // class CXformExplorationCXformImplementation类作为base class for all implementations，其定义如下所示：
class CXformImplementation : public CXform {
private: CXformImplementation(const CXformImplementation &); // private copy ctor
public:
explicit CXformImplementation(CExpression *); // ctor
virtual ~CXformImplementation(); // dtor
virtual BOOL FImplementation() const { // type of operator
return true;
}
}; // class CXformImplementation
CLogical |
EXformId |
CXform subclass |
Phase |
CLogicalAssert |
CXform::ExfImplementAssert |
||
CLogicalBitmapTableGet |
CXform::ExfImplementBitmapTableGet |
||
CLogicalConstTableGet |
CXform::ExfImplementConstTableGet |
||
CLogicalCTEAnchor |
CXform::ExfCTEAnchor2Sequence、CXform::ExfCTEAnchor2TrivialSelect |
||
CLogicalCTEConsumer |
CXform::ExfInlineCTEConsumer、CXform::ExfImplementCTEConsumer |
||
CLogicalCTEProducer |
CXform::ExfImplementCTEProducer |
||
CLogicalDelete |
CXform::ExfDelete2DML |
||
CLogicalDifference |
CXform::ExfDifference2LeftAntiSemiJoin |
||
CLogicalDifferenceAll |
CXform::ExfDifferenceAll2LeftAntiSemiJoin |
||
CLogicalDML |
CXform::ExfImplementDML |
||
CLogicalDynamicBitmapTableGet |
CXform::ExfImplementDynamicBitmapTableGet |
||
CLogicalDynamicGet |
CXform::ExfDynamicGet2DynamicTableScan、CXform::ExfExpandDynamicGetWithExternalPartitions |
||
CLogicalDynamicIndexGet |
CXform::ExfDynamicIndexGet2DynamicIndexScan |
||
CLogicalExternalGet |
CXform::ExfExternalGet2ExternalScan |
||
CLogicalFullOuterJoin |
CXform::ExfExpandFullOuterJoin、CXform::ExfImplementFullOuterMergeJoin |
||
CLogicalGbAgg |
CXform::ExfSimplifyGbAgg)、CXform::ExfGbAggWithMDQA2Join、CXform::ExfCollapseGbAgg、CXform::ExfPushGbBelowJoin、CXform::ExfPushGbBelowUnion、CXform::ExfPushGbBelowUnionAll、CXform::ExfSplitGbAgg、CXform::ExfSplitDQA、CXform::ExfGbAgg2Apply、CXform::ExfGbAgg2HashAgg、CXform::ExfGbAgg2StreamAgg、CXform::ExfGbAgg2ScalarAgg、CXform::ExfEagerAgg |
||
CLogicalGbAggDeduplicate |
CXform::ExfPushGbDedupBelowJoin、CXform::ExfSplitGbAggDedup、CXform::ExfGbAggDedup2HashAggDedup、CXform::ExfGbAggDedup2StreamAggDedup |
||
CLogicalGet |
CXform::ExfGet2TableScan |
||
CLogicalIndexApply |
CXform::ExfImplementIndexApply |
||
CLogicalIndexGet |
CXform::ExfIndexGet2IndexScan、CXform::ExfIndexGet2IndexOnlyScan |
||
CLogicalInnerApply |
CXform::ExfInnerApply2InnerJoin、CXform::ExfInnerApply2InnerJoinNoCorrelations、CXform::ExfInnerApplyWithOuterKey2InnerJoin |
||
CLogicalInnerCorrelatedApply |
CXform::ExfImplementInnerCorrelatedApply |
||
CLogicalInnerJoin |
CXform::ExfInnerJoin2NLJoin、CXform::ExfInnerJoin2HashJoin、CXform::ExfSubqJoin2Apply、CXform::ExfInnerJoin2PartialDynamicIndexGetApply、CXform::ExfInnerJoinWithInnerSelect2PartialDynamicIndexGetApply、CXform::ExfJoin2BitmapIndexGetApply、CXform::ExfJoin2IndexGetApply、CXform::ExfJoinCommutativity、CXform::ExfJoinAssociativity、CXform::ExfInnerJoinSemiJoinSwap、CXform::ExfInnerJoinAntiSemiJoinSwap、CXform::ExfInnerJoinAntiSemiJoinNotInSwap |
||
CLogicalInsert |
CXform::ExfInsert2DML |
||
CLogicalIntersect |
CXform::ExfIntersect2Join |
||
CLogicalIntersectAll |
CXform::ExfIntersectAll2LeftSemiJoin |
||
CLogicalLeftAntiSemiApply |
CXform::ExfLeftAntiSemiApply2LeftAntiSemiJoin、CXform::ExfLeftAntiSemiApply2LeftAntiSemiJoinNoCorrelations |
||
CLogicalLeftAntiSemiApplyNotIn |
CXform::ExfLeftAntiSemiApplyNotIn2LeftAntiSemiJoinNotIn、CXform::ExfLeftAntiSemiApplyNotIn2LeftAntiSemiJoinNotInNoCorrelations |
||
CLogicalLeftAntiSemiCorrelatedApply |
CXform::ExfImplementLeftAntiSemiCorrelatedApply |
||
CLogicalLeftAntiSemiCorrelatedApplyNotIn |
CXform::ExfImplementLeftAntiSemiCorrelatedApplyNotIn |
||
CLogicalLeftAntiSemiJoin |
CXform::ExfAntiSemiJoinAntiSemiJoinSwap、CXform::ExfAntiSemiJoinAntiSemiJoinNotInSwap、CXform::ExfAntiSemiJoinSemiJoinSwap、CXform::ExfAntiSemiJoinInnerJoinSwap、CXform::ExfLeftAntiSemiJoin2CrossProduct、CXform::ExfLeftAntiSemiJoin2NLJoin、CXform::ExfLeftAntiSemiJoin2HashJoin |
||
CLogicalLeftAntiSemiJoinNotIn |
CXform::ExfAntiSemiJoinNotInAntiSemiJoinNotInSwap、CXform::ExfAntiSemiJoinNotInAntiSemiJoinSwap、CXform::ExfAntiSemiJoinNotInSemiJoinSwap、CXform::ExfAntiSemiJoinNotInInnerJoinSwap、CXform::ExfLeftAntiSemiJoinNotIn2CrossProduct、CXform::ExfLeftAntiSemiJoinNotIn2NLJoinNotIn、CXform::ExfLeftAntiSemiJoinNotIn2HashJoinNotIn |
||
CLogicalLeftOuterApply |
CXform::ExfLeftOuterApply2LeftOuterJoin、CXform::ExfLeftOuterApply2LeftOuterJoinNoCorrelations |
||
CLogicalLeftOuterCorrelatedApply |
CXform::ExfImplementLeftOuterCorrelatedApply |
||
CLogicalLeftOuterJoin |
CXform::ExfPushDownLeftOuterJoin、CXform::ExfSimplifyLeftOuterJoin、CXform::ExfLeftOuterJoin2NLJoin、CXform::ExfLeftOuterJoin2HashJoin、CXform::ExfLeftOuter2InnerUnionAllLeftAntiSemiJoin、CXform::ExfJoin2BitmapIndexGetApply、CXform::ExfJoin2IndexGetApply、CXform::ExfLeftJoin2RightJoin |
||
CLogicalLeftSemiApply |
CXform::ExfLeftSemiApply2LeftSemiJoin、CXform::ExfLeftSemiApplyWithExternalCorrs2InnerJoin、CXform::ExfLeftSemiApply2LeftSemiJoinNoCorrelations |
||
CLogicalLeftSemiApplyIn |
CXform::ExfLeftSemiApplyIn2LeftSemiJoin、CXform::ExfLeftSemiApplyInWithExternalCorrs2InnerJoin、CXform::ExfLeftSemiApplyIn2LeftSemiJoinNoCorrelations |
||
CLogicalLeftSemiCorrelatedApply |
CXform::ExfImplementLeftSemiCorrelatedApply |
||
CLogicalLeftSemiCorrelatedApplyIn |
CXform::ExfImplementLeftSemiCorrelatedApplyIn |
||
CLogicalLeftSemiJoin |
CXform::ExfSemiJoinSemiJoinSwap、CXform::ExfSemiJoinAntiSemiJoinSwap、CXform::ExfSemiJoinAntiSemiJoinNotInSwap、CXform::ExfSemiJoinInnerJoinSwap、CXform::ExfLeftSemiJoin2InnerJoin、CXform::ExfLeftSemiJoin2InnerJoinUnderGb、CXform::ExfLeftSemiJoin2CrossProduct、CXform::ExfLeftSemiJoin2NLJoin、CXform::ExfLeftSemiJoin2HashJoin |
||
CLogicalLimit |
CXform::ExfImplementLimit、CXform::ExfSplitLimit |
||
CLogicalMaxOneRow |
CXform::ExfMaxOneRow2Assert |
||
CLogicalMultiExternalGet |
CXform::ExfMultiExternalGet2MultiExternalScan |
||
CLogicalNAryJoin |
CXform::ExfSubqNAryJoin2Apply、CXform::ExfExpandNAryJoin、CXform::ExfExpandNAryJoinMinCard、CXform::ExfExpandNAryJoinDP、CXform::ExfExpandNAryJoinGreedy、CXform::ExfExpandNAryJoinDPv2 |
||
CLogicalPartitionSelector |
CXform::ExfImplementPartitionSelector |
||
CLogicalProject |
CXform::ExfSimplifyProjectWithSubquery、CXform::ExfProject2Apply、CXform::ExfProject2ComputeScalar、CXform::ExfCollapseProject |
||
CLogicalRightOuterJoin |
CXform::ExfRightOuterJoin2HashJoin |
||
CLogicalRowTrigger |
CXform::ExfImplementRowTrigger |
||
CLogicalSelect |
CXform::ExfSelect2Apply、CXform::ExfRemoveSubqDistinct、CXform::ExfInlineCTEConsumerUnderSelect、CXform::ExfPushGbWithHavingBelowJoin、CXform::ExfSelect2IndexGet、CXform::ExfSelect2DynamicIndexGet、CXform::ExfSelect2PartialDynamicIndexGet、CXform::ExfSelect2BitmapBoolOp、CXform::ExfSelect2DynamicBitmapBoolOp、CXform::ExfSimplifySelectWithSubquery、CXform::ExfSelect2Filter |
||
CLogicalSequence |
CXform::ExfImplementSequence |
||
CLogicalSequenceProject |
CXform::ExfSequenceProject2Apply、CXform::ExfImplementSequenceProject |
||
CLogicalSplit |
CXform::ExfImplementSplit |
||
CLogicalTVF |
CXform::ExfUnnestTVF、CXform::ExfImplementTVF、CXform::ExfImplementTVFNoArgs |
||
CLogicalUnion |
CXform::ExfUnion2UnionAll |
||
CLogicalUnionAll |
CXform::ExfImplementUnionAll |
||
CLogicalUpdate |
CXform::ExfUpdate2DML |