org.apache.accumulo.core.client.sample

Class RowColumnSampler

java.lang.Object

org.apache.accumulo.core.client.sample.AbstractHashSampler

org.apache.accumulo.core.client.sample.RowColumnSampler

All Implemented Interfaces:

Sampler

public class RowColumnSampler
extends AbstractHashSampler

This sampler can hash any subset of a Key's fields. The fields that hashed for the sample are determined by the configuration options passed in init(SamplerConfiguration). The following key values are valid options.

• row=true|false
• family=true|false
• qualifier=true|false
• visibility=true|false

If not specified in the options, fields default to false.

To determine what options are valid for hashing see AbstractHashSampler

To configure Accumulo to generate sample data on one thousandth of the column qualifiers, the following SamplerConfiguration could be created and used to configure a table.

 
 new SamplerConfiguration(RowColumnSampler.class.getName()).setOptions(
   ImmutableMap.of("hasher","murmur3_32","modulus","1009","qualifier","true"));
 
 

With this configuration, if a column qualifier is selected then all key values contains that column qualifier will end up in the sample data.

Since:

1.8.0

Constructor Summary

Constructors

Constructor and Description
RowColumnSampler()

Method Summary

Modifier and Type	Method and Description
protected void	hash(DataOutput hasher, Key k) Subclass must override this method and hash some portion of the key.
void	init(SamplerConfiguration config) Subclasses with options should override this method and call super.init(config).
protected boolean	isValidOption(String option) Subclasses with options should override this method and return true if the option is valid for the subclass or if super.isValidOption(opt) returns true.

Methods inherited from class org.apache.accumulo.core.client.sample.AbstractHashSampler

accept

Methods inherited from class java.lang.Object

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

Constructor Detail

RowColumnSampler

public RowColumnSampler()

Method Detail

isValidOption

protected boolean isValidOption(String option)

Description copied from class: AbstractHashSampler

Subclasses with options should override this method and return true if the option is valid for the subclass or if super.isValidOption(opt) returns true.

Overrides:

isValidOption in class AbstractHashSampler

init

public void init(SamplerConfiguration config)

Description copied from class: AbstractHashSampler

Subclasses with options should override this method and call super.init(config).

Specified by:

init in interface Sampler

Overrides:

init in class AbstractHashSampler

Parameters:

config - Configuration options for a sampler.

hash

protected void hash(DataOutput hasher,
                    Key k)
             throws IOException

Description copied from class: AbstractHashSampler

Subclass must override this method and hash some portion of the key.

Specified by:

hash in class AbstractHashSampler

Parameters:

hasher - Data written to this will be used to compute the hash for the key.

Throws:

IOException