Class JavaScriptAggregatorFactory
- java.lang.Object
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- org.apache.druid.query.aggregation.AggregatorFactory
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- org.apache.druid.query.aggregation.JavaScriptAggregatorFactory
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- All Implemented Interfaces:
Cacheable
public class JavaScriptAggregatorFactory extends AggregatorFactory
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Constructor Summary
Constructors Constructor Description JavaScriptAggregatorFactory(String name, List<String> fieldNames, String fnAggregate, String fnReset, String fnCombine, JavaScriptConfig config)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Object
combine(Object lhs, Object rhs)
A method that knows how to combine the outputs ofAggregator.get()
produced viaAggregatorFactory.factorize(org.apache.druid.segment.ColumnSelectorFactory)
orBufferAggregator.get(java.nio.ByteBuffer, int)
produced viaAggregatorFactory.factorizeBuffered(org.apache.druid.segment.ColumnSelectorFactory)
.Object
deserialize(Object object)
A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.boolean
equals(Object o)
Aggregator
factorize(ColumnSelectorFactory columnFactory)
BufferAggregator
factorizeBuffered(ColumnSelectorFactory columnSelectorFactory)
@Nullable Object
finalizeComputation(@Nullable Object object)
"Finalizes" the computation of an object.byte[]
getCacheKey()
Get a byte array used as a cache key.AggregatorFactory
getCombiningFactory()
Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory.Comparator
getComparator()
List<String>
getFieldNames()
String
getFnAggregate()
String
getFnCombine()
String
getFnReset()
ColumnType
getIntermediateType()
Get the "intermediate"ColumnType
for this aggregator.int
getMaxIntermediateSize()
Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.AggregatorFactory
getMergingFactory(AggregatorFactory other)
Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory and another factory.String
getName()
ColumnType
getResultType()
Get theColumnType
for the final form of this aggregator, i.e.int
hashCode()
AggregateCombiner
makeAggregateCombiner()
Creates an AggregateCombiner to fold rollup aggregation results from serveral "rows" of different indexes during index merging.List<String>
requiredFields()
Get a list of fields that aggregators built by this factory will need to read.String
toString()
AggregatorFactory
withName(String newName)
Used in cases where we want to change the output name of the aggregator to something else.-
Methods inherited from class org.apache.druid.query.aggregation.AggregatorFactory
canVectorize, factorizeVector, factorizeWithSize, getComplexTypeName, getFinalizedType, getMaxIntermediateSizeWithNulls, getRequiredColumns, getType, guessAggregatorHeapFootprint, makeNullableAggregateCombiner, mergeAggregators, optimizeForSegment
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Method Detail
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factorize
public Aggregator factorize(ColumnSelectorFactory columnFactory)
- Specified by:
factorize
in classAggregatorFactory
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factorizeBuffered
public BufferAggregator factorizeBuffered(ColumnSelectorFactory columnSelectorFactory)
- Specified by:
factorizeBuffered
in classAggregatorFactory
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getComparator
public Comparator getComparator()
- Specified by:
getComparator
in classAggregatorFactory
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combine
public Object combine(Object lhs, Object rhs)
Description copied from class:AggregatorFactory
A method that knows how to combine the outputs ofAggregator.get()
produced viaAggregatorFactory.factorize(org.apache.druid.segment.ColumnSelectorFactory)
orBufferAggregator.get(java.nio.ByteBuffer, int)
produced viaAggregatorFactory.factorizeBuffered(org.apache.druid.segment.ColumnSelectorFactory)
. Note, even though this method is called "combine", this method's contract *does* allow for mutation of the input objects. Thus, any use of lhs or rhs after calling this method is highly discouraged.- Specified by:
combine
in classAggregatorFactory
- Parameters:
lhs
- The left hand side of the combinerhs
- The right hand side of the combine- Returns:
- an object representing the combination of lhs and rhs, this can be a new object or a mutation of the inputs
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makeAggregateCombiner
public AggregateCombiner makeAggregateCombiner()
Description copied from class:AggregatorFactory
Creates an AggregateCombiner to fold rollup aggregation results from serveral "rows" of different indexes during index merging. AggregateCombiner implements the same logic asAggregatorFactory.combine(java.lang.Object, java.lang.Object)
, with the difference that it usesColumnValueSelector
and it's subinterfaces to get inputs and implementsColumnValueSelector
to provide output.- Overrides:
makeAggregateCombiner
in classAggregatorFactory
- See Also:
AggregateCombiner
,IndexMerger
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getCombiningFactory
public AggregatorFactory getCombiningFactory()
Description copied from class:AggregatorFactory
Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory. It is used when we know we have some values that were produced with this aggregator factory, and want to do some additional combining of them. This happens, for example, when merging query results from two different segments, or two different servers. For simple aggregators, the combining factory may be computed by simply creating a new factory that is the same as the current, except with its input column renamed to the same as the output column. For example, this aggregator: {"type": "longSum", "fieldName": "foo", "name": "bar"} Would become: {"type": "longSum", "fieldName": "bar", "name": "bar"} Sometimes, the type or other parameters of the combining aggregator will be different from the original aggregator. For example, theCountAggregatorFactory
getCombiningFactory method will return aLongSumAggregatorFactory
, because counts are combined by summing. No matter what, `foo.getCombiningFactory()` and `foo.getCombiningFactory().getCombiningFactory()` should return the same result.- Specified by:
getCombiningFactory
in classAggregatorFactory
- Returns:
- a new Factory that can be used for operations on top of data output from the current factory.
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getMergingFactory
public AggregatorFactory getMergingFactory(AggregatorFactory other) throws AggregatorFactoryNotMergeableException
Description copied from class:AggregatorFactory
Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory and another factory. It is used when we have some values produced by this aggregator factory, and some values produced by the "other" aggregator factory, and we want to do some additional combining of them. This happens, for example, when compacting two segments together that both have a metric column with the same name. (Even though the name of the column is the same, the aggregator factory used to create it may be different from segment to segment.) This method may throwAggregatorFactoryNotMergeableException
, meaning that "this" and "other" are not compatible and values from one cannot sensibly be combined with values from the other.- Overrides:
getMergingFactory
in classAggregatorFactory
- Returns:
- a new Factory that can be used for merging the output of aggregators from this factory and other.
- Throws:
AggregatorFactoryNotMergeableException
- See Also:
which is equivalent to (when "this" and "other" are the same instance).
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deserialize
public Object deserialize(Object object)
Description copied from class:AggregatorFactory
A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.- Specified by:
deserialize
in classAggregatorFactory
- Parameters:
object
- the object to deserialize- Returns:
- the deserialized object
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finalizeComputation
public @Nullable Object finalizeComputation(@Nullable Object object)
Description copied from class:AggregatorFactory
"Finalizes" the computation of an object. Primarily useful for complex types that have a different mergeable intermediate format than their final resultant output.- Specified by:
finalizeComputation
in classAggregatorFactory
- Parameters:
object
- the object to be finalized- Returns:
- the finalized value that should be returned for the initial query
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getName
public String getName()
- Specified by:
getName
in classAggregatorFactory
- Returns:
- output name of the aggregator column.
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getFnAggregate
public String getFnAggregate()
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getFnReset
public String getFnReset()
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getFnCombine
public String getFnCombine()
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requiredFields
public List<String> requiredFields()
Description copied from class:AggregatorFactory
Get a list of fields that aggregators built by this factory will need to read.- Specified by:
requiredFields
in classAggregatorFactory
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getCacheKey
public byte[] getCacheKey()
Description copied from interface:Cacheable
Get a byte array used as a cache key.- Returns:
- a cache key
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getIntermediateType
public ColumnType getIntermediateType()
Description copied from class:AggregatorFactory
Get the "intermediate"ColumnType
for this aggregator. This is the same as the type returned byAggregatorFactory.deserialize(java.lang.Object)
and the type accepted byAggregatorFactory.combine(java.lang.Object, java.lang.Object)
. However, it is *not* necessarily the same type returned byAggregatorFactory.finalizeComputation(java.lang.Object)
. Refer to theColumnType
javadocs for details on the implications of choosing a type.- Overrides:
getIntermediateType
in classAggregatorFactory
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getResultType
public ColumnType getResultType()
Description copied from class:AggregatorFactory
Get theColumnType
for the final form of this aggregator, i.e. the type of the value returned byAggregatorFactory.finalizeComputation(java.lang.Object)
. This may be the same as or different than the types expected inAggregatorFactory.deserialize(java.lang.Object)
andAggregatorFactory.combine(java.lang.Object, java.lang.Object)
. Refer to theColumnType
javadocs for details on the implications of choosing a type.- Overrides:
getResultType
in classAggregatorFactory
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getMaxIntermediateSize
public int getMaxIntermediateSize()
Description copied from class:AggregatorFactory
Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.- Specified by:
getMaxIntermediateSize
in classAggregatorFactory
- Returns:
- the maximum number of bytes that an aggregator of this type will require for intermediate result storage.
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withName
public AggregatorFactory withName(String newName)
Description copied from class:AggregatorFactory
Used in cases where we want to change the output name of the aggregator to something else. For eg: if we have a query `select a, sum(b) as total group by a from table` the aggregator returned from the native group by query is "a0" set inorg.apache.druid.sql.calcite.rel.DruidQuery#computeAggregations
. We can use withName("total") to set the output name of the aggregator to "total".As all implementations of this interface method may not exist, callers of this method are advised to handle such a case.
- Overrides:
withName
in classAggregatorFactory
- Parameters:
newName
- newName of the output for aggregator factory- Returns:
- AggregatorFactory with the output name set as the input param.
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