class XxxValueExprPlan : public XxxGenericPlan

An expression plan is used to evaluate an expression (i

Inheritance:

Public Classes

class

VarRemapping A VarRemapping helps modify an expression plan through join order changes struct SrcMapping* SrcMappingArray / array that specifies the new mapping int* NewAttrMapping mappings for child attrs

Public Methods

virtual XxxErrCode	Accumulate (const XxxRecord* Rec[], const XxxRecordSchema* Schema[], XxxAggrOpHandle *Handle, const XxxValueEnv* Env = NULL) / Accumulate into handle
XxxErrCode	Evaluate (const XxxRecord* Rec, const XxxRecordSchema* Schema, XxxADTValue *Result, const XxxValueEnv* Env = NULL) / evaluate, when there is a single input
virtual XxxErrCode	GetDependencies (XxxBitMap& Dependendency) / Similar method for XxxExpression as well
virtual XxxErrCode	Init (XxxAggrOpHandle *Handle) / Initialize handle
virtual XxxErrCode	MakeOpHandle (XxxAggrOpHandle*& Handle) / Make a handle to hold ongoing aggregation
virtual XxxErrCode	RedirectDependencies (const VarRemapping& Remap, int CorrelationHeight = 0)
virtual XxxGenericPlan*	Replicate () Replication
virtual XxxErrCode	Terminate (XxxAggrOpHandle *Handle, const XxxRecord* Rec[], const XxxRecordSchema* Schema[], XxxADTValue *FinalVal, const XxxValueEnv* Env = NULL) / Terminates the aggregation and performs any postprocessing
virtual XxxErrCode	UsageOfPlan (PlanUsage& Usage) / member of XxxGenericPlan
	XxxValueExprPlan (XxxExpression * Exp, XxxValueExprPlan* Children[]) this is the most commonly used constructor
	XxxValueExprPlan (const XxxValueExprPlan &Plan) Copy constructor
	XxxValueExprPlan (int Arity, XxxBool Constant, XxxValueExprPlan* Children[])

Public

	/ Gets input stream dependencies.
	/ 4 methods to evaluate an aggregate expression

Protected Methods

XxxErrCode

changeDependency (const VarRemapping& Remap) this method will be called from RedirectDependencies

Private Fields

XxxValueExpression*

sourceExpr / a copy of the source expression (needed for index expressions)

XxxValueExpression* sourceExpr

/ a copy of the source expression (needed for index expressions)

class VarRemapping

A VarRemapping helps modify an expression plan through join order changes. Every variable (XxxUnknownValue) in an expression gets resolved with a SrcChild and SrcAttrIndex during type checking. These persist into the ExprPlan. However, during join optimization, a query block can be split into several different join operators with a different join order. The ExprPlans need to be suitably modified to reflect this. The VarReMapping provides the necessary information to do so.

struct SrcMapping* SrcMappingArray

/ array that specifies the new mapping

int* NewAttrMapping

mappings for child attrs

XxxErrCode changeDependency(const VarRemapping& Remap)

this method will be called from RedirectDependencies

XxxValueExprPlan(XxxExpression * Exp, XxxValueExprPlan* Children[])

this is the most commonly used constructor

XxxValueExprPlan(const XxxValueExprPlan &Plan)

Copy constructor

XxxValueExprPlan(int Arity, XxxBool Constant, XxxValueExprPlan* Children[])

virtual XxxGenericPlan* Replicate()

Replication

XxxErrCode Evaluate(const XxxRecord* Rec, const XxxRecordSchema* Schema, XxxADTValue *Result, const XxxValueEnv* Env = NULL)

/ evaluate, when there is a single input

/ 4 methods to evaluate an aggregate expression

virtual XxxErrCode MakeOpHandle(XxxAggrOpHandle*& Handle)

/ Make a handle to hold ongoing aggregation

virtual XxxErrCode Init(XxxAggrOpHandle *Handle)

/ Initialize handle

virtual XxxErrCode Accumulate(const XxxRecord* Rec[], const XxxRecordSchema* Schema[], XxxAggrOpHandle *Handle, const XxxValueEnv* Env = NULL)

/ Accumulate into handle

virtual XxxErrCode Terminate(XxxAggrOpHandle *Handle, const XxxRecord* Rec[], const XxxRecordSchema* Schema[], XxxADTValue *FinalVal, const XxxValueEnv* Env = NULL)

/ Terminates the aggregation and performs any postprocessing

virtual XxxErrCode UsageOfPlan(PlanUsage& Usage)

/ member of XxxGenericPlan

/ Gets input stream dependencies.

virtual XxxErrCode GetDependencies(XxxBitMap& Dependendency)

/ Similar method for XxxExpression as well

virtual XxxErrCode RedirectDependencies(const VarRemapping& Remap, int CorrelationHeight = 0)

Direct child classes:

UnknownValuePlan
FuncPlan
ConstPlan
CastPlan
XxxBooleanExpressionPlan
ArithPlan
ArgValuePlan

Author:

Praveen

See Also:

XxxGenericPlan

alphabetic index hierarchy of classes

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