Module datarush.library
Package com.pervasive.datarush.ports.record

Class DataOrdering

java.lang.Object
com.pervasive.datarush.ports.record.DataOrdering
public final class DataOrdering extends Object
DataOrdering is the component of RecordMetadata that describes how the data is ordered.

Operators may declare a required ordering by calling RecordPort.setRequiredDataOrdering(com.pervasive.datarush.operators.MetadataCalculationContext, com.pervasive.datarush.ports.record.DataOrdering). It is the responsibility of the framework to ensure that the specified requirement is met. Operators may also declare their output ordering by calling RecordPort.setOutputDataDistribution(com.pervasive.datarush.operators.MetadataCalculationContext, com.pervasive.datarush.ports.record.DataDistribution). This lets the framework know how data is ordered on the operator's output. If there is an mismatch between required and provided metadata, the framework will automatically sort as needed.

See Also:
  • StreamingOperator#computeMetadata
  • IterativeOperator#computeMetadata

  • Field Details

    • UNSPECIFIED

      public static final DataOrdering UNSPECIFIED
      The default data ordering if not specified.

  • Constructor Details

    • DataOrdering

      public DataOrdering(List<SortKey> keys)
      Specify that data is ordered by the given set of keys.
      Parameters:
      keys - specifies field names and ascending vs. descending

    • DataOrdering

      public DataOrdering(SortKey[] keys)
      Specify that data is ordered by the given set of keys.
      Parameters:
      keys - specifies field names and ascending vs. descending

  • Method Details

    • isOrdered

      public boolean isOrdered(SortKey[] desired)
      Returns true if data is ordered by the specified ordering or a prefix of the specified ordering.
      Parameters:
      desired - the desired data ordering
      Returns:
      whether the data is ordered by the desired ordering

    • isOrdered

      public boolean isOrdered(String[] desired)
      Returns true if data is ordered by the specified ordering or a prefix of the specified ordering. This method ignores ascending vs. descending order. If ascending vs. descending is important use isOrdered(SortKey[]) instead.
      Parameters:
      desired - the desired data ordering
      Returns:
      whether the data is ordered by the desired ordering

    • getAliases

      public AliasSet[] getAliases()

    • getKeys

      public SortKey[] getKeys()
      Returns the keys that the data is sorted by
      Returns:
      the keys the date data is sorted by

    • isUnspecified

      public boolean isUnspecified()
      Returns whether this is the unspecified data ordering. The unspecified data ordering is equivalent to an ordering where there are no sort keys.
      Returns:
      whether this is the unspecified data ordering

    • getPrefixOrdering

      public SortKey[] getPrefixOrdering(String[] prefix)
      Returns a prefix of the current ordering, merged with sort direction information. This is useful for operators that require data be sorted by a specific set of keys but have no specific requirements regarding sort direction. Those operators will first need to test whether data is ordered as desired by calling isOrdered(String[]). If data is ordered, they will then call this method to determine specific directional information.
      Parameters:
      prefix - must be a prefix of the data ordering
      Returns:
      a prefix of the current ordering.
      Throws:
      IllegalArgumentException - if the data is not ordered by the given prefix

    • remap

      public DataOrdering remap(FieldRemapping mapping)
      Applies the given field remapping to this ordering, changing names as required. If any sort keys refer to columns that are dropped as part of the rename, the result ordering will be a prefix of the original. If all sort keys refer to columns that are dropped via the rename, the result will be the UNSPECIFIED ordering.
      Parameters:
      mapping - the field remapping.
      Returns:
      this distribution, remapped to the new names.

    • toString

      public String toString()
      Overrides:
      toString in class Object