org.apache.fluo.recipes.core.data

Class RowHasher

java.lang.Object

org.apache.fluo.recipes.core.data.RowHasher

public class RowHasher
extends Object

This recipe provides code to help add a hash of the row as a prefix of the row. Using this recipe rows are structured like the following.

<prefix>:<fixed len row hash>:<user row>

The recipe also provides code the help generate split points and configure balancing of the prefix.

The project documentation has more information.

A single instance of RowHasher is thread safe. Creating a single static instance and using it can result in good performance.

Since:

1.0.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RowHasher.Optimizer

Constructor Summary

Constructors

Constructor and Description
RowHasher(String prefix)

Method Summary

Modifier and Type	Method and Description
org.apache.fluo.api.data.Bytes	addHash(org.apache.fluo.api.data.Bytes row)
org.apache.fluo.api.data.Bytes	addHash(String row)
static void	configure(org.apache.fluo.api.config.FluoConfiguration fluoConfig, String prefix, int numTablets) This method can be called to register table optimizations before initializing Fluo.
String	getPrefix()
org.apache.fluo.api.data.Bytes	removeHash(org.apache.fluo.api.data.Bytes row)

Methods inherited from class java.lang.Object

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

Constructor Detail

RowHasher

public RowHasher(String prefix)

Method Detail

configure

public static void configure(org.apache.fluo.api.config.FluoConfiguration fluoConfig,
                             String prefix,
                             int numTablets)

This method can be called to register table optimizations before initializing Fluo. This will register RowHasher.Optimizer with TableOptimizations.registerOptimization(SimpleConfiguration, String, Class). See the project level documentation for an example.

Parameters:

fluoConfig - The config that will be used to initialize Fluo

prefix - The prefix used for your Row Hasher. If you have a single instance, could call getPrefix().

numTablets - Initial number of tablet to create.

getPrefix

public String getPrefix()

addHash

public org.apache.fluo.api.data.Bytes addHash(String row)

Returns:

Returns input with prefix and hash of input prepended.

addHash

public org.apache.fluo.api.data.Bytes addHash(org.apache.fluo.api.data.Bytes row)

Returns:

Returns input with prefix and hash of input prepended.

removeHash

public org.apache.fluo.api.data.Bytes removeHash(org.apache.fluo.api.data.Bytes row)

Returns:

Returns input with prefix and hash stripped from beginning.