Package org.elasticsearch.search.aggregations.metrics

Class CardinalityAggregator

java.lang.Object

org.elasticsearch.search.aggregations.BucketCollector

org.elasticsearch.search.aggregations.Aggregator

org.elasticsearch.search.aggregations.AggregatorBase

org.elasticsearch.search.aggregations.metrics.MetricsAggregator

org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator

org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator.SingleValue

org.elasticsearch.search.aggregations.metrics.CardinalityAggregator

All Implemented Interfaces:

Closeable, AutoCloseable, org.apache.lucene.search.Collector, org.elasticsearch.core.Releasable

public class CardinalityAggregator
extends NumericMetricsAggregator.SingleValue

An aggregator that computes approximate counts of unique values.

Nested Class Summary

Nested classes/interfaces inherited from class org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator

NumericMetricsAggregator.MultiValue, NumericMetricsAggregator.SingleValue

Nested classes/interfaces inherited from class org.elasticsearch.search.aggregations.Aggregator

Aggregator.BucketComparator, Aggregator.Parser, Aggregator.SubAggCollectionMode

Field Summary

Fields inherited from class org.elasticsearch.search.aggregations.AggregatorBase

collectableSubAggregators, DEFAULT_WEIGHT, name, parent, subAggregators

Fields inherited from class org.elasticsearch.search.aggregations.BucketCollector

NO_OP_COLLECTOR

Constructor Summary

Constructors

Constructor	Description
CardinalityAggregator(String name, ValuesSourceConfig valuesSourceConfig, int precision, AggregationContext context, Aggregator parent, Map<String,Object> metadata)

Method Summary

Modifier and Type	Method	Description
InternalAggregation	buildAggregation(long owningBucketOrdinal)	Build an aggregation for data that has been collected into owningBucketOrd.
InternalAggregation	buildEmptyAggregation()	Build an empty aggregation.
void	collectDebugInfo(BiConsumer<String,Object> add)	Collect debug information to add to the profiling results.
protected void	doClose()	Release instance-specific data.
protected void	doPostCollection()	Can be overridden by aggregator implementation to be called back when the collection phase ends.
LeafBucketCollector	getLeafCollector(org.apache.lucene.index.LeafReaderContext ctx, LeafBucketCollector sub)	Collect results for this leaf.
double	metric(long owningBucketOrd)
org.apache.lucene.search.ScoreMode	scoreMode()	Most aggregators don't need scores, make sure to extend this method if your aggregator needs them.

Methods inherited from class org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator.SingleValue

bucketComparator

Methods inherited from class org.elasticsearch.search.aggregations.metrics.MetricsAggregator

buildAggregations

Methods inherited from class org.elasticsearch.search.aggregations.AggregatorBase

addRequestCircuitBreakerBytes, bigArrays, buildEmptySubAggregations, close, doPreCollection, getLeafCollector, metadata, name, parent, pointReaderIfAvailable, postCollection, preCollection, preGetSubLeafCollectors, searcher, subAggregator, subAggregators, topLevelQuery, toString

Methods inherited from class org.elasticsearch.search.aggregations.Aggregator

buildTopLevel, resolveSortPath, resolveSortPathOnValidAgg

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

CardinalityAggregator

public CardinalityAggregator(String name,
 ValuesSourceConfig valuesSourceConfig,
 int precision,
 AggregationContext context,
 Aggregator parent,
 Map<String,Object> metadata)
                      throws IOException

Throws:

IOException

Method Details

scoreMode

public org.apache.lucene.search.ScoreMode scoreMode()

Description copied from class: AggregatorBase

Most aggregators don't need scores, make sure to extend this method if your aggregator needs them.

Specified by:

scoreMode in interface org.apache.lucene.search.Collector

Overrides:

scoreMode in class AggregatorBase

getLeafCollector

public LeafBucketCollector getLeafCollector(org.apache.lucene.index.LeafReaderContext ctx,
 LeafBucketCollector sub)
                                     throws IOException

Description copied from class: AggregatorBase

Collect results for this leaf.

Most Aggregators will return a custom LeafBucketCollector that collects document information for every hit. Callers of this method will make sure to call collect for every hit. So any Aggregator that returns a customer LeafBucketCollector from this method runs at best O(hits) time. See the sum Aggregator for a fairly strait forward example of this.

Some Aggregators are able to correctly collect results on their own, without being iterated by the top level query or the rest of the aggregations framework. These aggregations collect what they need by calling methods on LeafReaderContext and then they return LeafBucketCollector.NO_OP_COLLECTOR to signal that they've done their own collection. These aggregations can do better than O(hits). See the min Aggregator for an example of an aggregation that does this. It happens to run in constant time in some cases.

In other cases MinAggregator can't get correct results by taking the constant time path so instead it returns a custom LeafBucketCollector. This is fairly common for aggregations that have these fast paths because most of these fast paths are only possible when the aggregation is at the root of the tree.

Its also useful to look at the filters Aggregator chooses whether or not it can use the fast path before building the Aggregator rather than on each leaf. Either is fine.

Specified by:

getLeafCollector in class AggregatorBase

Throws:

IOException

doPostCollection

protected void doPostCollection()
                         throws IOException

Description copied from class: AggregatorBase

Can be overridden by aggregator implementation to be called back when the collection phase ends.

Overrides:

doPostCollection in class AggregatorBase

Throws:

IOException

metric

public double metric(long owningBucketOrd)

Specified by:

metric in class NumericMetricsAggregator.SingleValue

buildAggregation

public InternalAggregation buildAggregation(long owningBucketOrdinal)

Description copied from class: MetricsAggregator

Build an aggregation for data that has been collected into owningBucketOrd.

Specified by:

buildAggregation in class MetricsAggregator

buildEmptyAggregation

public InternalAggregation buildEmptyAggregation()

Description copied from class: Aggregator

Build an empty aggregation.

Specified by:

buildEmptyAggregation in class Aggregator

doClose

protected void doClose()

Description copied from class: AggregatorBase

Release instance-specific data.

Overrides:

doClose in class AggregatorBase

collectDebugInfo

public void collectDebugInfo(BiConsumer<String,Object> add)

Description copied from class: Aggregator

Collect debug information to add to the profiling results. This will only be called if the aggregation is being profiled.

Well behaved implementations will always call the superclass implementation just in case it has something interesting. They will also only add objects which can be serialized with StreamOutput.writeGenericValue(Object) and XContentBuilder.value(Object). And they'll have an integration test.

Overrides:

collectDebugInfo in class Aggregator