Module org.elasticsearch.server

Package org.elasticsearch.search.aggregations.bucket.sampler

Class SamplerAggregator

java.lang.Object

org.elasticsearch.search.aggregations.BucketCollector

org.elasticsearch.search.aggregations.Aggregator

org.elasticsearch.search.aggregations.AggregatorBase

org.elasticsearch.search.aggregations.bucket.BucketsAggregator

org.elasticsearch.search.aggregations.bucket.DeferableBucketAggregator

org.elasticsearch.search.aggregations.bucket.sampler.SamplerAggregator

All Implemented Interfaces:

Closeable, AutoCloseable, Releasable, SingleBucketAggregator

Direct Known Subclasses:

DiversifiedBytesHashSamplerAggregator, DiversifiedMapSamplerAggregator, DiversifiedNumericSamplerAggregator, DiversifiedOrdinalsSamplerAggregator

public class SamplerAggregator
extends DeferableBucketAggregator
implements SingleBucketAggregator

Aggregate on only the top-scoring docs on a shard. TODO currently the diversity feature of this agg offers only 'script' and 'field' as a means of generating a de-dup value. In future it would be nice if users could use any of the "bucket" aggs syntax (geo, date histogram...) as the basis for generating de-dup values. Their syntax for creating bucket values would be preferable to users having to recreate this logic in a 'script' e.g. to turn a datetime in milliseconds into a month key value.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	SamplerAggregator.ExecutionMode

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

BucketsAggregator.BucketBuilderForFixedCount<B>, BucketsAggregator.BucketBuilderForVariable<B>, BucketsAggregator.ResultBuilderForVariable<B>, BucketsAggregator.SingleBucketResultBuilder

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

Aggregator.BucketComparator, Aggregator.Parser, Aggregator.SubAggCollectionMode

Field Summary

Fields

Modifier and Type	Field	Description
protected BestDocsDeferringCollector	bdd
static final ParseField	EXECUTION_HINT_FIELD
static final ParseField	MAX_DOCS_PER_VALUE_FIELD
static final ParseField	SHARD_SIZE_FIELD
protected final int	shardSize

Fields inherited from class org.elasticsearch.search.aggregations.bucket.BucketsAggregator

docCountProvider

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_BUCKET_COLLECTOR, NO_OP_COLLECTOR

Method Summary

Modifier and Type	Method	Description
InternalAggregation[]	buildAggregations(long[] owningBucketOrds)	Build the results of this aggregation.
DeferringBucketCollector	buildDeferringCollector()	Build the DeferringBucketCollector.
InternalAggregation	buildEmptyAggregation()	Build an empty aggregation.
protected void	doClose()	Release instance-specific data.
protected LeafBucketCollector	getLeafCollector(AggregationExecutionContext aggCtx, LeafBucketCollector sub)	Collect results for this leaf.
org.apache.lucene.search.ScoreMode	scoreMode()	Most aggregators don't need scores, make sure to extend this method if your aggregator needs them.
protected boolean	shouldDefer(Aggregator aggregator)	This method should be overridden by subclasses that want to defer calculation of a child aggregation until a first pass is complete and a set of buckets has been pruned.

Methods inherited from class org.elasticsearch.search.aggregations.bucket.DeferableBucketAggregator

collectDebugInfo, deferringCollector, doPreCollection, prepareSubAggs

Methods inherited from class org.elasticsearch.search.aggregations.bucket.BucketsAggregator

bucketComparator, bucketDocCount, buildAggregationsForFixedBucketCount, buildAggregationsForSingleBucket, buildAggregationsForVariableBuckets, buildSubAggsForAllBuckets, buildSubAggsForBuckets, buildSubAggsForBuckets, close, collectBucket, collectExistingBucket, descendsFromGlobalAggregator, getDocCounts, grow, incrementBucketDocCount, maxBucketOrd, preGetSubLeafCollectors, resolveSortPath, rewriteBuckets

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

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

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

buildTopLevel, resolveSortPathOnValidAgg

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

asCollector

Methods inherited from class java.lang.Object

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

Field Details

SHARD_SIZE_FIELD

public static final ParseField SHARD_SIZE_FIELD

MAX_DOCS_PER_VALUE_FIELD

public static final ParseField MAX_DOCS_PER_VALUE_FIELD

EXECUTION_HINT_FIELD

public static final ParseField EXECUTION_HINT_FIELD

shardSize

protected final int shardSize

bdd

protected BestDocsDeferringCollector bdd

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.

Overrides:

scoreMode in class AggregatorBase

buildDeferringCollector

public DeferringBucketCollector buildDeferringCollector()

Description copied from class: DeferableBucketAggregator

Build the DeferringBucketCollector. The default implementation replays all hits against the buckets selected by {#link DeferringBucketCollector.prepareSelectedBuckets(long...).

Overrides:

buildDeferringCollector in class DeferableBucketAggregator

shouldDefer

protected boolean shouldDefer(Aggregator aggregator)

Description copied from class: DeferableBucketAggregator

This method should be overridden by subclasses that want to defer calculation of a child aggregation until a first pass is complete and a set of buckets has been pruned.

Overrides:

shouldDefer in class DeferableBucketAggregator

Parameters:

aggregator - the child aggregator

Returns:

true if the aggregator should be deferred until a first pass at collection has completed

buildAggregations

public InternalAggregation[] buildAggregations(long[] owningBucketOrds)
                                        throws IOException

Description copied from class: Aggregator

Build the results of this aggregation.

Specified by:

buildAggregations in class Aggregator

Parameters:

owningBucketOrds - the ordinals of the buckets that we want to collect from this aggregation

Returns:

the results for each ordinal, in the same order as the array of ordinals

Throws:

IOException

buildEmptyAggregation

public InternalAggregation buildEmptyAggregation()

Description copied from class: Aggregator

Build an empty aggregation.

Specified by:

buildEmptyAggregation in class Aggregator

getLeafCollector

protected LeafBucketCollector getLeafCollector(AggregationExecutionContext aggCtx,
 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

doClose

protected void doClose()

Description copied from class: AggregatorBase

Release instance-specific data.

Overrides:

doClose in class AggregatorBase