io.crate.metadata

Class FunctionInfo

java.lang.Object

io.crate.metadata.FunctionInfo

All Implemented Interfaces:

java.lang.Comparable<FunctionInfo>, org.elasticsearch.common.io.stream.Streamable

public class FunctionInfo
extends java.lang.Object
implements java.lang.Comparable<FunctionInfo>, org.elasticsearch.common.io.stream.Streamable

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FunctionInfo.Type

Constructor Summary

Constructors

Constructor and Description
FunctionInfo()
FunctionInfo(FunctionIdent ident, DataType returnType)
FunctionInfo(FunctionIdent ident, DataType returnType, FunctionInfo.Type type)
FunctionInfo(FunctionIdent ident, DataType returnType, FunctionInfo.Type type, boolean deterministic, boolean comparisonReplacementPossible)

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(FunctionInfo o)
boolean	comparisonReplacementPossible() If this method returns true, for this function it is possible to replace the containing comparison while preserving the truth value for all used operators with or without an operator mapping.
boolean	equals(java.lang.Object o)
int	hashCode()
FunctionIdent	ident()
boolean	isDeterministic()
void	readFrom(org.elasticsearch.common.io.stream.StreamInput in)
DataType	returnType()
java.lang.String	toString()
FunctionInfo.Type	type()
void	writeTo(org.elasticsearch.common.io.stream.StreamOutput out)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

FunctionInfo

public FunctionInfo()

FunctionInfo

public FunctionInfo(FunctionIdent ident,
            DataType returnType)

FunctionInfo

public FunctionInfo(FunctionIdent ident,
            DataType returnType,
            FunctionInfo.Type type)

FunctionInfo

public FunctionInfo(FunctionIdent ident,
            DataType returnType,
            FunctionInfo.Type type,
            boolean deterministic,
            boolean comparisonReplacementPossible)

Method Detail

ident

public FunctionIdent ident()

type

public FunctionInfo.Type type()

isDeterministic

public boolean isDeterministic()

returnType

public DataType returnType()

comparisonReplacementPossible

public boolean comparisonReplacementPossible()

If this method returns true, for this function it is possible to replace the containing comparison while preserving the truth value for all used operators with or without an operator mapping. It describes the following: say we have a comparison-query like this: col > 10.5 then a function f, for which comparions are replaceable, can be applied so that: f(col) > f(10.5) for all col for which col > 10.5 is true. Maybe > needs to be mapped to another operator, but this may not depend on the actual values used here. Fun facts: * This property holds for the = comparison operator for all functions f. * This property is transitive so if f and g are replaceable, then f(g(x)) also is * it is possible to replace: col > 10.5 with: f(col) > f(10.5) for every operator (possibly mapped) and the query is still equivalent. Example 1: if f is defined as f(v) = v + 1 then col + 1 > 11.5 must be true for all col > 10.5. This is indeed true. So f is replaceable for >. Fun fact: for f all comparison operators =, >, <, >=,<= are replaceable Example 2 (a rounding function): if f is defined as f(v) = ceil(v) then ceil(col) > 11 for all col > 10.5. But there is 10.8 for which f is 11 and 11 > 11 is false. Here a simple mapping of the operator will do the trick: > -> >= < -> <= So for f comparisons are replaceable using the mapping above. Example 3: if f is defined as f(v) = v % 5 then col % 5 > 0.5 for all col > 10.5 but there is 20 for which f is 0 and 0 > 0.5 is false. So for f comparisons cannot be replaced.

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

compareTo

public int compareTo(FunctionInfo o)

Specified by:

compareTo in interface java.lang.Comparable<FunctionInfo>

readFrom

public void readFrom(org.elasticsearch.common.io.stream.StreamInput in)
              throws java.io.IOException

Specified by:

readFrom in interface org.elasticsearch.common.io.stream.Streamable

Throws:

java.io.IOException

writeTo

public void writeTo(org.elasticsearch.common.io.stream.StreamOutput out)
             throws java.io.IOException

Specified by:

writeTo in interface org.elasticsearch.common.io.stream.Streamable

Throws:

java.io.IOException