Package org.pentaho.di.trans

Interface Partitioner

All Known Implementing Classes:
BasePartitioner, ModPartitioner
public interface Partitioner
Defines methods needed for partitioner plugins. The main responsibilities are:
  • Maintain partitioner settings
    The implementing class typically keeps track of partitioner settings using private fields with corresponding getters and setters. The dialog class implementing StepDialogInterface is using the getters and setters to copy the user supplied configuration in and out of the dialog.

    The following interface method also falls into the area of maintaining settings:

    public Object clone()

    This method is called when a step containing partitioning configuration is duplicated in Spoon. It needs to return a deep copy of this partitioner object. It is essential that the implementing class creates proper deep copies if the configuration is stored in modifiable objects, such as lists or custom helper objects. The copy is created by first calling super.clone(), and deep-copying any fields the partitioner may have declared.

    public Partitioner getInstance()

    This method is required to return a new instance of the partitioner class, with the plugin id and plugin description inherited from the instance this function is called on.

  • Serialize partitioner settings
    The plugin needs to be able to serialize its settings to both XML and a PDI repository. The interface methods are as follows.

    public String getXML()

    This method is called by PDI whenever the plugin needs to serialize its settings to XML. It is called when saving a transformation in Spoon. The method returns an XML string, containing the serialized settings. The string contains a series of XML tags, typically one tag per setting. The helper class org.pentaho.di.core.xml.XMLHandler is typically used to construct the XML string.

    public void loadXML(...)

    This method is called by PDI whenever a plugin needs to read its settings from XML. The XML node containing the plugin's settings is passed in as an argument. Again, the helper class org.pentaho.di.core.xml.XMLHandler is typically used to conveniently read the settings from the XML node.

    public void saveRep(...)

    This method is called by PDI whenever a plugin needs to save its settings to a PDI repository. The repository object passed in as the first argument provides a convenient set of methods for serializing settings. The transformation id and step id passed in should be used as identifiers when calling the repository serialization methods.

    public void loadRep(...)

    This method is called by PDI whenever a plugin needs to read its configuration from a PDI repository. The step id given in the arguments should be used as the identifier when using the repositories serialization methods.

  • Provide access to dialog class
    • PDI needs to know which class will take care of the settings dialog for the plugin. The interface method must return the name of the class implementing the StepDialogInterface for the partitioner.

    public String getDialogClassName()

  • Partition incoming rows during runtime
    The class implementing Partitioner executes the actual logic that distributes the rows to available partitions.

    This method is called with the row structure and the actual row as arguments. It must return the partition this row will be sent to. The total number of partitions is available in the inherited field nrPartitions, and the return value must be between 0 and nrPartitions-1.

    public int getPartition(...)

  • Method Details

    • getInstance

      Partitioner getInstance()
      Gets the single instance of Partitioner.
      Returns:
      single instance of Partitioner

    • getPartition

      int getPartition(org.pentaho.di.core.row.RowMetaInterface rowMeta, Object[] r) throws org.pentaho.di.core.exception.KettleException
      Gets the partition.
      Parameters:
      rowMeta - the row meta
      r - the r
      Returns:
      the partition
      Throws:
      org.pentaho.di.core.exception.KettleException - the kettle exception

    • setMeta

      void setMeta(StepPartitioningMeta meta)
      Sets the meta.
      Parameters:
      meta - the new meta

    • getId

      String getId()
      Gets the id.
      Returns:
      the id

    • getDescription

      String getDescription()
      Gets the description.
      Returns:
      the description

    • setId

      void setId(String id)
      Sets the id.
      Parameters:
      id - the new id

    • setDescription

      void setDescription(String description)
      Sets the description.
      Parameters:
      description - the new description

    • getDialogClassName

      String getDialogClassName()
      Gets the dialog class name.
      Returns:
      the dialog class name

    • clone

      Partitioner clone()
      Clone.
      Returns:
      the partitioner

    • getXML

      String getXML()
      Gets the xml.
      Returns:
      the xml

    • loadXML

      void loadXML(Node partitioningMethodNode) throws org.pentaho.di.core.exception.KettleXMLException
      Load xml.
      Parameters:
      partitioningMethodNode - the partitioning method node
      Throws:
      org.pentaho.di.core.exception.KettleXMLException - the kettle xml exception

    • saveRep

      void saveRep(Repository rep, org.pentaho.di.repository.ObjectId id_transformation, org.pentaho.di.repository.ObjectId id_step) throws org.pentaho.di.core.exception.KettleException
      Saves partitioning properties in the repository for the given step.
      Parameters:
      rep - the repository to save in
      id_transformation - the ID of the transformation
      id_step - the ID of the step
      Throws:
      org.pentaho.di.core.exception.KettleException - In case anything goes wrong

    • loadRep

      void loadRep(Repository rep, org.pentaho.di.repository.ObjectId id_step) throws org.pentaho.di.core.exception.KettleException
      Load rep.
      Parameters:
      rep - the rep
      id_step - the id_step
      Throws:
      org.pentaho.di.core.exception.KettleException - the kettle exception