Class SystemAggregator
java.lang.Object
org.apache.derby.impl.sql.execute.SystemAggregator
- All Implemented Interfaces:
Externalizable
,Serializable
,Formatable
,TypedFormat
,ExecAggregator
- Direct Known Subclasses:
CountAggregator
,OrderableAggregator
Abstract aggregator that is extended by all internal
(system) aggregators.
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected abstract void
accumulate
(DataValueDescriptor addend) void
accumulate
(DataValueDescriptor addend, Object ga) Iteratively accumulates the addend into the aggregator.boolean
Return true if the aggregation eliminated at least one null from the input data set.void
toString()
void
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface org.apache.derby.iapi.sql.execute.ExecAggregator
getResult, merge, newAggregator, setup
Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat
getTypeFormatId
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Field Details
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eliminatedNulls
private boolean eliminatedNulls
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Constructor Details
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SystemAggregator
SystemAggregator()
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Method Details
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didEliminateNulls
public boolean didEliminateNulls()Description copied from interface:ExecAggregator
Return true if the aggregation eliminated at least one null from the input data set.- Specified by:
didEliminateNulls
in interfaceExecAggregator
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accumulate
Description copied from interface:ExecAggregator
Iteratively accumulates the addend into the aggregator. Called on each member of the set of values that is being aggregated.- Specified by:
accumulate
in interfaceExecAggregator
- Parameters:
addend
- the DataValueDescriptor addend (current input to the aggregation)ga
- a result set getter- Throws:
StandardException
- on error
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accumulate
- Throws:
StandardException
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writeExternal
- Specified by:
writeExternal
in interfaceExternalizable
- Throws:
IOException
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readExternal
- Specified by:
readExternal
in interfaceExternalizable
- Throws:
IOException
ClassNotFoundException
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toString
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