Package org.apache.accumulo.core.client.mapreduce

Class InputTableConfig

java.lang.Object
org.apache.accumulo.core.client.mapreduce.InputTableConfig
All Implemented Interfaces:
org.apache.hadoop.io.Writable
public class InputTableConfig extends Object implements org.apache.hadoop.io.Writable
This class to holds a batch scan configuration for a table. It contains all the properties needed to specify how rows should be returned from the table.

  • Constructor Details

    • InputTableConfig

      public InputTableConfig()

    • InputTableConfig

      public InputTableConfig(DataInput input) throws IOException
      Creates a batch scan config object out of a previously serialized batch scan config object.
      Parameters:
      input - the data input of the serialized batch scan config
      Throws:
      IOException

  • Method Details

    • setRanges

      public InputTableConfig setRanges(List<Range> ranges)
      Sets the input ranges to scan for all tables associated with this job. This will be added to any per-table ranges that have been set using
      Parameters:
      ranges - the ranges that will be mapped over
      Since:
      1.6.0

    • getRanges

      public List<Range> getRanges()
      Returns the ranges to be queried in the configuration

    • fetchColumns

      public InputTableConfig fetchColumns(Collection<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>> columns)
      Restricts the columns that will be mapped over for this job for the default input table.
      Parameters:
      columns - 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:
      1.6.0

    • getFetchedColumns

      public Collection<org.apache.accumulo.core.util.Pair<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>> getFetchedColumns()
      Returns the columns to be fetched for this configuration

    • setIterators

      public InputTableConfig setIterators(List<IteratorSetting> iterators)
      Set iterators on to be used in the query.
      Parameters:
      iterators - the configurations for the iterators
      Since:
      1.6.0

    • getIterators

      public List<IteratorSetting> getIterators()
      Returns the iterators to be set on this configuration

    • setAutoAdjustRanges

      public InputTableConfig setAutoAdjustRanges(boolean autoAdjustRanges)
      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:
      autoAdjustRanges - the feature is enabled if true, disabled otherwise
      Since:
      1.6.0
      See Also:

    • shouldAutoAdjustRanges

      public boolean shouldAutoAdjustRanges()
      Determines whether a configuration has auto-adjust ranges enabled.
      Returns:
      false if the feature is disabled, true otherwise
      Since:
      1.6.0
      See Also:

    • setUseLocalIterators

      public InputTableConfig setUseLocalIterators(boolean useLocalIterators)
      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:
      useLocalIterators - the feature is enabled if true, disabled otherwise
      Since:
      1.6.0

    • shouldUseLocalIterators

      public boolean shouldUseLocalIterators()
      Determines whether a configuration uses local iterators.
      Returns:
      true if the feature is enabled, false otherwise
      Since:
      1.6.0
      See Also:

    • setOfflineScan

      public InputTableConfig setOfflineScan(boolean offlineScan)
      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. The accumulo-site.xml may need to be on the mapper's classpath if HDFS or the Accumulo directory in HDFS are non-standard.

      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:
      offlineScan - the feature is enabled if true, disabled otherwise
      Since:
      1.6.0

    • isOfflineScan

      public boolean isOfflineScan()
      Determines whether a configuration has the offline table scan feature enabled.
      Returns:
      true if the feature is enabled, false otherwise
      Since:
      1.6.0
      See Also:

    • setUseIsolatedScanners

      public InputTableConfig setUseIsolatedScanners(boolean useIsolatedScanners)
      Controls the use of the IsolatedScanner in this job.

      By default, this feature is disabled.

      Parameters:
      useIsolatedScanners - the feature is enabled if true, disabled otherwise
      Since:
      1.6.0

    • shouldUseIsolatedScanners

      public boolean shouldUseIsolatedScanners()
      Determines whether a configuration has isolation enabled.
      Returns:
      true if the feature is enabled, false otherwise
      Since:
      1.6.0
      See Also:

    • setSamplerConfiguration

      public void setSamplerConfiguration(SamplerConfiguration samplerConfiguration)
      Set the sampler configuration to use when reading from the data.
      Since:
      1.8.0
      See Also:

    • getSamplerConfiguration

      public SamplerConfiguration getSamplerConfiguration()
      Since:
      1.8.0

    • write

      public void write(DataOutput dataOutput) throws IOException
      Specified by:
      write in interface org.apache.hadoop.io.Writable
      Throws:
      IOException

    • readFields

      public void readFields(DataInput dataInput) throws IOException
      Specified by:
      readFields in interface org.apache.hadoop.io.Writable
      Throws:
      IOException

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object