Examples of org.apache.derby.iapi.sql.execute.ExecAggregator

Package org.apache.derby.iapi.sql.execute

Examples of org.apache.derby.iapi.sql.execute.ExecAggregator

org.apache.derby.iapi.sql.execute.ExecAggregator
An ExecAggregator is the interface that execution uses to an aggregate. System defined aggregates will implement this directly.
The life time of an ExecAggregator is as follows.
1. An ExecAggregator instance is created using the defined class name.
2. Its setup() method is called to define its role (COUNT(*), SUM, etc.).
3. Its newAggregator() method may be called any number of times to create new working aggregators as required. These aggregators have the same role and must be created in an initialized state.
4. accumlate and merge will be called across these set of aggregators
5. One of these aggregators will be used as the final one for obtaining the result

      SanityManager.ASSERT(row != null, "row is null");
    }


    UserDataValue aggregatorColumn = (UserDataValue) row.getColumn(aggregatorColumnId + 1);


    ExecAggregator ua = (ExecAggregator) aggregatorColumn.getObject();
    if (ua == null)
    {
      ua = getAggregatorInstance();
      aggregatorColumn.setValue(ua);
    }

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   */
  void accumulate(DataValueDescriptor  inputColumn, 
              DataValueDescriptor  aggregatorColumn)
    throws StandardException
  {
    ExecAggregator    ua;


    if (SanityManager.DEBUG)
    {
      /*
      ** Just to be on the safe side, confirm that we actually
      ** have a Aggregator in this column.
      */
      if (!(aggregatorColumn instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("accumlator column is not a UserDataValue as "+
          "expected, it is a "+aggregatorColumn.getClass().getName());
      }
    }
    ua = (ExecAggregator) aggregatorColumn.getObject();


    /*
    ** If we don't have an aggregator, then we have to
    ** create one now.  This happens when the input result
    ** set is null.
    */
    if (ua == null)
    {
      ua = getAggregatorInstance();
    }
  
    ua.accumulate(inputColumn, this);
  }

View Full Code Here

      SanityManager.ASSERT(outputColumn != null, "otuputColumn is null");
      SanityManager.ASSERT(aggregatorColumn instanceof UserDataValue,
        "accumlator column is not a UserDataValue as expected");
    }


    ExecAggregator ua = (ExecAggregator) aggregatorColumn.getObject();


    /*
    ** If we don't have an aggregator, then we have to
    ** create one now.  This happens when the input result
    ** set is null.
    */
    if (ua == null)
    {
      ua = getAggregatorInstance();
    }  


    /*
    **
    ** We are going to copy
    ** then entire DataValueDescriptor into the result column.
    ** We could call setValue(result.setObject()), but we
    ** might loose state (e.g. SQLBit.getObject() returns a
    ** byte[] which looses the precision of the bit.  
    **
    */
    
    DataValueDescriptor result = ua.getResult();
    if (result == null)
      outputColumn.setToNull();
    else
      outputColumn.setValue(result);


    return ua.didEliminateNulls();
  }

View Full Code Here

   * @exception StandardException on error
   */
  ExecAggregator getAggregatorInstance()
    throws StandardException
  {
    ExecAggregator aggregatorInstance;
    if (cachedAggregator == null)
    {
      try
      {
        Class aggregatorClass = cf.loadApplicationClass(aggInfo.getAggregatorClassName());
        Object agg = aggregatorClass.newInstance();
        aggregatorInstance = (ExecAggregator)agg;
        cachedAggregator = aggregatorInstance;


        aggregatorInstance.setup
                    (
                     cf,
                     aggInfo.getAggregateName(),
                     aggInfo.getResultDescription().getColumnInfo()[ 0 ].getType()
                     );

View Full Code Here

   */
  void merge(Storable aggregatorColumnIn,
            Storable aggregatorColumnOut)
    throws StandardException
  {
    ExecAggregator  uaIn;
    ExecAggregator  uaOut;


    if (SanityManager.DEBUG)
    {
      /*
      ** Just to be on the safe side, confirm that we actually
      ** have a Aggregator in this column.
      */
      if (!(aggregatorColumnIn instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("aggregatorColumnOut column is not "+
          "a UserAggreator as expected, "+
          "it is a "+aggregatorColumnIn.getClass().getName());
      }
      if (!(aggregatorColumnOut instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("aggregatorColumnIn column is not"+
          " a UserAggreator as expected, "+
          "it is a "+aggregatorColumnOut.getClass().getName());
      }
    }
    uaIn = (ExecAggregator)(((UserDataValue) aggregatorColumnIn).getObject());
    uaOut = (ExecAggregator)(((UserDataValue) aggregatorColumnOut).getObject());


    uaOut.merge(uaIn);
  }

View Full Code Here

   * @exception StandardException  on error
   */
  void initialize(ExecRow row)
    throws StandardException
  {
    ExecAggregator    ua;
    UserDataValue  aggregatorColumn;


    if (SanityManager.DEBUG)
    {
      SanityManager.ASSERT(row != null, "row is null");

View Full Code Here

   */
  void accumulate(DataValueDescriptor  inputColumn, 
              DataValueDescriptor  aggregatorColumn)
    throws StandardException
  {
    ExecAggregator    ua;


    if (SanityManager.DEBUG)
    {
      /*
      ** Just to be on the safe side, confirm that we actually
      ** have a Aggregator in this column.
      */
      if (!(aggregatorColumn instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("accumlator column is not a UserDataValue as "+
          "expected, it is a "+aggregatorColumn.getClass().getName());
      }
    }
    ua = (ExecAggregator) aggregatorColumn.getObject();


    /*
    ** If we don't have an aggregator, then we have to
    ** create one now.  This happens when the input result
    ** set is null.
    */
    if (ua == null)
    {
      ua = getAggregatorInstance();
    }
  
    ua.accumulate(inputColumn, this);
  }

View Full Code Here

      SanityManager.ASSERT(outputColumn != null, "otuputColumn is null");
      SanityManager.ASSERT(aggregatorColumn instanceof UserDataValue,
        "accumlator column is not a UserDataValue as expected");
    }


    ExecAggregator ua = (ExecAggregator) aggregatorColumn.getObject();


    /*
    ** If we don't have an aggregator, then we have to
    ** create one now.  This happens when the input result
    ** set is null.
    */
    if (ua == null)
    {
      ua = getAggregatorInstance();
    }  


    Object result = ua.getResult();


    /*
    ** Handle setting the result.  If null, call setToNull.
    **
    ** If we got a DataValueDescriptor then we are going to copy
    ** then entire DataValueDescriptor into the result column.
    ** We could call setValue(result.setObject()), but we
    ** might loose state (e.g. SQLBit.getObject() returns a
    ** byte[] which looses the precision of the bit.  
    **
    ** On an object, just call setValue().
    */
    if (result == null)
    {
      outputColumn.setToNull();
    }
    /*
    ** See above as to why we cannot do: 
    **    outputColumn.setValue(result.getObject());  
    */
    else if (result instanceof DataValueDescriptor)
    {
      row.setColumn(resultColumnId + 1, (DataValueDescriptor)result);
    }
    else
    {
      outputColumn.setValue(result);
    }


    return ua.didEliminateNulls();
  }

View Full Code Here

   * @exception StandardException on error
   */
  ExecAggregator getAggregatorInstance()
    throws StandardException
  {
    ExecAggregator aggregatorInstance;
    if (cachedAggregator == null)
    {
      try
      {
        Class aggregatorClass = cf.loadApplicationClass(aggInfo.getAggregatorClassName());
        Object agg = aggregatorClass.newInstance();
        aggregatorInstance = (ExecAggregator)agg;
        cachedAggregator = aggregatorInstance;
        aggregatorInstance.setup(aggInfo.getAggregateName());


      } catch (Exception e)
      {
        throw StandardException.unexpectedUserException(e);
      }

View Full Code Here

   */
  void merge(Storable aggregatorColumnIn,
            Storable aggregatorColumnOut)
    throws StandardException
  {
    ExecAggregator  uaIn;
    ExecAggregator  uaOut;


    if (SanityManager.DEBUG)
    {
      /*
      ** Just to be on the safe side, confirm that we actually
      ** have a Aggregator in this column.
      */
      if (!(aggregatorColumnIn instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("aggregatorColumnOut column is not "+
          "a UserAggreator as expected, "+
          "it is a "+aggregatorColumnIn.getClass().getName());
      }
      if (!(aggregatorColumnOut instanceof UserDataValue))
      {
        SanityManager.THROWASSERT("aggregatorColumnIn column is not"+
          " a UserAggreator as expected, "+
          "it is a "+aggregatorColumnOut.getClass().getName());
      }
    }
    uaIn = (ExecAggregator)(((UserDataValue) aggregatorColumnIn).getObject());
    uaOut = (ExecAggregator)(((UserDataValue) aggregatorColumnOut).getObject());


    uaOut.merge(uaIn);
  }

View Full Code Here

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