org.apache.accumulo.core.client.mapreduce

Class InputFormatBase<K,V>

java.lang.Object

org.apache.hadoop.mapreduce.InputFormat<K,V>

org.apache.accumulo.core.client.mapreduce.AbstractInputFormat<K,V>

org.apache.accumulo.core.client.mapreduce.InputFormatBase<K,V>

Direct Known Subclasses:

AccumuloInputFormat, AccumuloRowInputFormat

public abstract class InputFormatBase<K,V>
extends AbstractInputFormat<K,V>

This abstract InputFormat class allows MapReduce jobs to use Accumulo as the source of K,V pairs.

Subclasses must implement a InputFormat.createRecordReader(InputSplit, TaskAttemptContext) to provide a RecordReader for K,V.

A static base class, RecordReaderBase, is provided to retrieve Accumulo Key/Value pairs, but one must implement its RecordReader.nextKeyValue() to transform them to the desired generic types K,V.

See AccumuloInputFormat for an example implementation.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	InputFormatBase.RangeInputSplit Deprecated. since 1.5.2; Use RangeInputSplit instead.
protected static class	InputFormatBase.RecordReaderBase<K,V>

Nested classes/interfaces inherited from class org.apache.accumulo.core.client.mapreduce.AbstractInputFormat

AbstractInputFormat.AbstractRecordReader<K,V>

Field Summary

Fields inherited from class org.apache.accumulo.core.client.mapreduce.AbstractInputFormat

CLASS, log

Constructor Summary

Constructors

Constructor and Description
InputFormatBase()

Method Summary

Modifier and Type	Method and Description
static void	addIterator(org.apache.hadoop.mapreduce.Job job, IteratorSetting cfg) Encode an iterator on the single input table for this job.
static void	fetchColumns(org.apache.hadoop.mapreduce.Job job, Collection<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>> columnFamilyColumnQualifierPairs) Restricts the columns that will be mapped over for this job for the default input table.
protected static boolean	getAutoAdjustRanges(org.apache.hadoop.mapreduce.JobContext context) Determines whether a configuration has auto-adjust ranges enabled.
protected static Set<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>>	getFetchedColumns(org.apache.hadoop.mapreduce.JobContext context) Gets the columns to be mapped over from this job.
protected static String	getInputTableName(org.apache.hadoop.mapreduce.JobContext context) Gets the table name from the configuration.
protected static List<IteratorSetting>	getIterators(org.apache.hadoop.mapreduce.JobContext context) Gets a list of the iterator settings (for iterators to apply to a scanner) from this configuration.
protected static List<Range>	getRanges(org.apache.hadoop.mapreduce.JobContext context) Gets the ranges to scan over from a job.
protected static org.apache.accumulo.core.client.impl.TabletLocator	getTabletLocator(org.apache.hadoop.mapreduce.JobContext context) Deprecated. since 1.6.0
static boolean	isBatchScan(org.apache.hadoop.mapreduce.JobContext context) Determines whether a configuration has the BatchScanner feature enabled.
protected static boolean	isIsolated(org.apache.hadoop.mapreduce.JobContext context) Determines whether a configuration has isolation enabled.
protected static boolean	isOfflineScan(org.apache.hadoop.mapreduce.JobContext context) Determines whether a configuration has the offline table scan feature enabled.
static void	setAutoAdjustRanges(org.apache.hadoop.mapreduce.Job job, boolean enableFeature) Controls the automatic adjustment of ranges for this job.
static void	setBatchScan(org.apache.hadoop.mapreduce.Job job, boolean enableFeature) Controls the use of the BatchScanner in this job.
static void	setInputTableName(org.apache.hadoop.mapreduce.Job job, String tableName) Sets the name of the input table, over which this job will scan.
static void	setLocalIterators(org.apache.hadoop.mapreduce.Job job, boolean enableFeature) Controls the use of the ClientSideIteratorScanner in this job.
static void	setOfflineTableScan(org.apache.hadoop.mapreduce.Job job, boolean enableFeature) Enable reading offline tables.
static void	setRanges(org.apache.hadoop.mapreduce.Job job, Collection<Range> ranges) Sets the input ranges to scan for the single input table associated with this job.
static void	setScanIsolation(org.apache.hadoop.mapreduce.Job job, boolean enableFeature) Controls the use of the IsolatedScanner in this job.
protected static boolean	usesLocalIterators(org.apache.hadoop.mapreduce.JobContext context) Determines whether a configuration uses local iterators.

Methods inherited from class org.apache.accumulo.core.client.mapreduce.AbstractInputFormat

getAuthenticationToken, getClientConfiguration, getInputTableConfig, getInputTableConfigs, getInstance, getLogLevel, getPrincipal, getScanAuthorizations, getSplits, getTabletLocator, getToken, getTokenClass, isConnectorInfoSet, setConnectorInfo, setConnectorInfo, setLogLevel, setMockInstance, setScanAuthorizations, setZooKeeperInstance, setZooKeeperInstance, validateOptions

Methods inherited from class org.apache.hadoop.mapreduce.InputFormat

createRecordReader

Methods inherited from class java.lang.Object

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

Constructor Detail

InputFormatBase

public InputFormatBase()

Method Detail

getInputTableName

protected static String getInputTableName(org.apache.hadoop.mapreduce.JobContext context)

Gets the table name from the configuration.

Parameters:

context - the Hadoop context for the configured job

Returns:

the table name

Since:

1.5.0

See Also:

setInputTableName(Job, String)

setInputTableName

public static void setInputTableName(org.apache.hadoop.mapreduce.Job job,
                                     String tableName)

Sets the name of the input table, over which this job will scan.

Parameters:

job - the Hadoop job instance to be configured

tableName - the table to use when the tablename is null in the write call

Since:

1.5.0

setRanges

public static void setRanges(org.apache.hadoop.mapreduce.Job job,
                             Collection<Range> ranges)

Sets the input ranges to scan for the single input table associated with this job.

Parameters:

job - the Hadoop job instance to be configured

ranges - the ranges that will be mapped over

Since:

1.5.0

getRanges

protected static List<Range> getRanges(org.apache.hadoop.mapreduce.JobContext context)
                                throws IOException

Gets the ranges to scan over from a job.

Parameters:

context - the Hadoop context for the configured job

Returns:

the ranges

Throws:

IOException

Since:

1.5.0

See Also:

setRanges(Job, Collection)

fetchColumns

public static void fetchColumns(org.apache.hadoop.mapreduce.Job job,
                                Collection<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>> columnFamilyColumnQualifierPairs)

Restricts the columns that will be mapped over for this job for the default input table.

Parameters:

job - the Hadoop job instance to be configured

columnFamilyColumnQualifierPairs - a pair of Text objects corresponding to column family and column qualifier. If the column qualifier is null, the entire column family is selected. An empty set is the default and is equivalent to scanning the all columns.

Since:

1.5.0

getFetchedColumns

protected static Set<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>> getFetchedColumns(org.apache.hadoop.mapreduce.JobContext context)

Gets the columns to be mapped over from this job.

Parameters:

context - the Hadoop context for the configured job

Returns:

a set of columns

Since:

1.5.0

See Also:

fetchColumns(Job, Collection)

addIterator

public static void addIterator(org.apache.hadoop.mapreduce.Job job,
                               IteratorSetting cfg)

Encode an iterator on the single input table for this job.

Parameters:

job - the Hadoop job instance to be configured

cfg - the configuration of the iterator

Since:

1.5.0

getIterators

protected static List<IteratorSetting> getIterators(org.apache.hadoop.mapreduce.JobContext context)

Gets a list of the iterator settings (for iterators to apply to a scanner) from this configuration.

Parameters:

context - the Hadoop context for the configured job

Returns:

a list of iterators

Since:

1.5.0

See Also:

addIterator(Job, IteratorSetting)

setAutoAdjustRanges

public static void setAutoAdjustRanges(org.apache.hadoop.mapreduce.Job job,
                                       boolean enableFeature)

Controls the automatic adjustment of ranges for this job. This feature merges overlapping ranges, then splits them to align with tablet boundaries. Disabling this feature will cause exactly one Map task to be created for each specified range. The default setting is enabled. *

By default, this feature is enabled.

Parameters:

job - the Hadoop job instance to be configured

enableFeature - the feature is enabled if true, disabled otherwise

Since:

1.5.0

See Also:

setRanges(Job, Collection)

getAutoAdjustRanges

protected static boolean getAutoAdjustRanges(org.apache.hadoop.mapreduce.JobContext context)

Determines whether a configuration has auto-adjust ranges enabled. Must be enabled when setBatchScan(Job, boolean) is true.

Parameters:

context - the Hadoop context for the configured job

Returns:

false if the feature is disabled, true otherwise

Since:

1.5.0

See Also:

setAutoAdjustRanges(Job, boolean)

setScanIsolation

public static void setScanIsolation(org.apache.hadoop.mapreduce.Job job,
                                    boolean enableFeature)

Controls the use of the IsolatedScanner in this job.

By default, this feature is disabled.

Parameters:

job - the Hadoop job instance to be configured

enableFeature - the feature is enabled if true, disabled otherwise

Since:

1.5.0

isIsolated

protected static boolean isIsolated(org.apache.hadoop.mapreduce.JobContext context)

Determines whether a configuration has isolation enabled.

Parameters:

context - the Hadoop context for the configured job

Returns:

true if the feature is enabled, false otherwise

Since:

1.5.0

See Also:

setScanIsolation(Job, boolean)

setLocalIterators

public static void setLocalIterators(org.apache.hadoop.mapreduce.Job job,
                                     boolean enableFeature)

Controls the use of the ClientSideIteratorScanner in this job. Enabling this feature will cause the iterator stack to be constructed within the Map task, rather than within the Accumulo TServer. To use this feature, all classes needed for those iterators must be available on the classpath for the task.

By default, this feature is disabled.

Parameters:

job - the Hadoop job instance to be configured

enableFeature - the feature is enabled if true, disabled otherwise

Since:

1.5.0

usesLocalIterators

protected static boolean usesLocalIterators(org.apache.hadoop.mapreduce.JobContext context)

Determines whether a configuration uses local iterators.

Parameters:

context - the Hadoop context for the configured job

Returns:

true if the feature is enabled, false otherwise

Since:

1.5.0

See Also:

setLocalIterators(Job, boolean)

setOfflineTableScan

public static void setOfflineTableScan(org.apache.hadoop.mapreduce.Job job,
                                       boolean enableFeature)

Enable reading offline tables. By default, this feature is disabled and only online tables are scanned. This will make the map reduce job directly read the table's files. If the table is not offline, then the job will fail. If the table comes online during the map reduce job, it is likely that the job will fail.

To use this option, the map reduce user will need access to read the Accumulo directory in HDFS.

Reading the offline table will create the scan time iterator stack in the map process. So any iterators that are configured for the table will need to be on the mapper's classpath.

One way to use this feature is to clone a table, take the clone offline, and use the clone as the input table for a map reduce job. If you plan to map reduce over the data many times, it may be better to the compact the table, clone it, take it offline, and use the clone for all map reduce jobs. The reason to do this is that compaction will reduce each tablet in the table to one file, and it is faster to read from one file.

There are two possible advantages to reading a tables file directly out of HDFS. First, you may see better read performance. Second, it will support speculative execution better. When reading an online table speculative execution can put more load on an already slow tablet server.

By default, this feature is disabled.

Parameters:

job - the Hadoop job instance to be configured

enableFeature - the feature is enabled if true, disabled otherwise

Since:

1.5.0

isOfflineScan

protected static boolean isOfflineScan(org.apache.hadoop.mapreduce.JobContext context)

Determines whether a configuration has the offline table scan feature enabled.

Parameters:

context - the Hadoop context for the configured job

Returns:

true if the feature is enabled, false otherwise

Since:

1.5.0

See Also:

setOfflineTableScan(Job, boolean)

setBatchScan

public static void setBatchScan(org.apache.hadoop.mapreduce.Job job,
                                boolean enableFeature)

Controls the use of the BatchScanner in this job. Using this feature will group Ranges by their source tablet, producing an InputSplit per tablet rather than per Range. This batching helps to reduce overhead when querying a large number of small ranges. (ex: when doing quad-tree decomposition for spatial queries)

In order to achieve good locality of InputSplits this option always clips the input Ranges to tablet boundaries. This may result in one input Range contributing to several InputSplits.

Note: that the value of setAutoAdjustRanges(Job, boolean) is ignored and is assumed to be true when BatchScan option is enabled.

This configuration is incompatible with:

• setOfflineTableScan(org.apache.hadoop.mapreduce.Job, boolean)
• setLocalIterators(org.apache.hadoop.mapreduce.Job, boolean)
• setScanIsolation(org.apache.hadoop.mapreduce.Job, boolean)

By default, this feature is disabled.

Parameters:

job - the Hadoop job instance to be configured

enableFeature - the feature is enabled if true, disabled otherwise

Since:

1.7.0

isBatchScan

public static boolean isBatchScan(org.apache.hadoop.mapreduce.JobContext context)

Determines whether a configuration has the BatchScanner feature enabled.

Parameters:

context - the Hadoop context for the configured job

Since:

1.7.0

See Also:

setBatchScan(Job, boolean)

getTabletLocator

@Deprecated
protected static org.apache.accumulo.core.client.impl.TabletLocator getTabletLocator(org.apache.hadoop.mapreduce.JobContext context)
                                                                                          throws TableNotFoundException

Deprecated. since 1.6.0

Initializes an Accumulo TabletLocator based on the configuration.

Parameters:

context - the Hadoop context for the configured job

Returns:

an Accumulo tablet locator

Throws:

TableNotFoundException - if the table name set on the configuration doesn't exist

Since:

1.5.0