Package org.apache.cassandra.cql3.selection

Class Selector

java.lang.Object

org.apache.cassandra.cql3.selection.Selector

Direct Known Subclasses:

SimpleSelector, TermSelector

public abstract class Selector
extends java.lang.Object

A Selector is used to convert the data returned by the storage engine into the data requested by the user. They correspond to the <selector> elements from the select clause.

Since the introduction of aggregation, Selectors cannot be called anymore by multiple threads as they have an internal state.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Selector.Factory	A factory for Selector instances.

Constructor Summary

Constructors

Constructor	Description
Selector()

Method Summary

Modifier and Type	Method	Description
abstract void	addFetchedColumns(ColumnFilter.Builder builder)	Add to the provided builder the column (and potential subselections) to fetch for this selection.
abstract void	addInput(ProtocolVersion protocolVersion, ResultSetBuilder rs)	Add the current value from the specified ResultSetBuilder.
abstract java.nio.ByteBuffer	getOutput(ProtocolVersion protocolVersion)	Returns the selector output.
abstract AbstractType<?>	getType()	Returns the Selector output type.
abstract void	reset()	Reset the internal state of this Selector.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Selector

public Selector()

Method Detail

addFetchedColumns

public abstract void addFetchedColumns(ColumnFilter.Builder builder)

Add to the provided builder the column (and potential subselections) to fetch for this selection.

Parameters:

builder - the builder to add columns and subselections to.

addInput

public abstract void addInput(ProtocolVersion protocolVersion,
                              ResultSetBuilder rs)
                       throws InvalidRequestException

Add the current value from the specified ResultSetBuilder.

Parameters:

protocolVersion - protocol version used for serialization

rs - the ResultSetBuilder

Throws:

InvalidRequestException - if a problem occurs while add the input value

getOutput

public abstract java.nio.ByteBuffer getOutput(ProtocolVersion protocolVersion)
                                       throws InvalidRequestException

Returns the selector output.

Parameters:

protocolVersion - protocol version used for serialization

Returns:

the selector output

Throws:

InvalidRequestException - if a problem occurs while computing the output value

getType

public abstract AbstractType<?> getType()

Returns the Selector output type.

Returns:

the Selector output type.

reset

public abstract void reset()

Reset the internal state of this Selector.