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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-522) GenericUDAF: Extend UDAF to deal with complex types
Date Fri, 29 May 2009 05:28:45 GMT

    [ https://issues.apache.org/jira/browse/HIVE-522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714300#action_12714300
] 

Zheng Shao commented on HIVE-522:
---------------------------------

Interface for GenericUDAF.

{code:java}
interface GenericUDAF {

  enum {
    /** Partial: from original data to partial aggregation data: iterate() and terminatePartial()
will be called */
    PARTIAL,
    /** Merge: from partial aggregation to full aggregation: merge() and terminate() will
be called */
    MERGE,
    /** Full: from original data directly to full aggregation: merge() and terminate() will
be called */
    FULL
  } Mode;

  /** Initialize the aggregation.
   *  @param m  The mode of aggregation.
   *  @param parameters  The ObjectInspector for the parameters:
   *    In PARTIAL and FULL mode, the parameters are original data;
   *    In MERGE mode, the parameters are just partial aggregations (in that case, the array
will always have a single element).
   *  @return  The ObjectInspector for the return value.
   *    In PARTIAL mode, the ObjectInspector for the return value of terminatePartial() call;
   *    In MERGE and FULL mode, the ObjectInspector for the return value of terminate() call.
   */
  OI init(Mode m, ObjectInspector[] parameters);

  /** Iterate through raw data.
   *  @param parameters  The objects of parameters.
   */
  void iterate(Object[] parameters);

  /** Get partial aggregation result.
   *  @return partial aggregation result.
   */
  Object terminatePartial();

  /** Merge with partial aggregation result.
   *  @param partial  The partial aggregation result.
   */
  void merge(Object partial);

  /** Get final aggregation result.
   *  @return final aggregation result.
   */
  Object terminate();

};

{code}



> GenericUDAF: Extend UDAF to deal with complex types
> ---------------------------------------------------
>
>                 Key: HIVE-522
>                 URL: https://issues.apache.org/jira/browse/HIVE-522
>             Project: Hadoop Hive
>          Issue Type: New Feature
>          Components: Query Processor
>    Affects Versions: 0.4.0
>            Reporter: Zheng Shao
>            Assignee: Zheng Shao
>
> We can pass arbitrary arguments into GenericUDFs. We should do the same thing to GenericUDAF
so that UDAF can also take arbitrary arguments.

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