Package org.apache.lucene.search
Class CachingCollector
java.lang.Object
org.apache.lucene.search.FilterCollector
org.apache.lucene.search.CachingCollector
- All Implemented Interfaces:
Collector
Caches all docs, and optionally also scores, coming from a search, and is then able to replay
them to another collector. You specify the max RAM this class may use. Once the collection is
done, call
isCached()
. If this returns true, you can use replay(Collector)
against a new collector. If it returns false, this means too much RAM was required and you must
instead re-run the original search.
NOTE: this class consumes 4 (or 8 bytes, if scoring is cached) per collected document. If the result set is large this can easily be a very substantial amount of RAM!
See the Lucene modules/grouping
module for more details including a full code
example.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Field Summary
Fields inherited from class org.apache.lucene.search.FilterCollector
in
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Method Summary
Modifier and TypeMethodDescriptionstatic CachingCollector
create
(boolean cacheScores, double maxRAMMB) Creates aCachingCollector
which does not wrap another collector.static CachingCollector
Create a newCachingCollector
that wraps the given collector and caches documents and scores up to the specified RAM threshold.static CachingCollector
Create a newCachingCollector
that wraps the given collector and caches documents and scores up to the specified max docs threshold.final boolean
isCached()
Return true is this collector is able to replay collection.abstract void
Replays the cached doc IDs (and scores) to the given Collector.Methods inherited from class org.apache.lucene.search.FilterCollector
getLeafCollector, scoreMode, toString
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Method Details
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create
Creates aCachingCollector
which does not wrap another collector. The cached documents and scores can later bereplayed
. -
create
Create a newCachingCollector
that wraps the given collector and caches documents and scores up to the specified RAM threshold.- Parameters:
other
- the Collector to wrap and delegate calls to.cacheScores
- whether to cache scores in addition to document IDs. Note that this increases the RAM consumed per docmaxRAMMB
- the maximum RAM in MB to consume for caching the documents and scores. If the collector exceeds the threshold, no documents and scores are cached.
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create
Create a newCachingCollector
that wraps the given collector and caches documents and scores up to the specified max docs threshold.- Parameters:
other
- the Collector to wrap and delegate calls to.cacheScores
- whether to cache scores in addition to document IDs. Note that this increases the RAM consumed per docmaxDocsToCache
- the maximum number of documents for caching the documents and possible the scores. If the collector exceeds the threshold, no documents and scores are cached.
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isCached
public final boolean isCached()Return true is this collector is able to replay collection. -
replay
Replays the cached doc IDs (and scores) to the given Collector. If this instance does not cache scores, then Scorer is not set onother.setScorer
as well as scores are not replayed.- Throws:
IllegalStateException
- if this collector is not cached (i.e., if the RAM limits were too low for the number of documents + scores to cache).IllegalArgumentException
- if the given Collect's does not support out-of-order collection, while the collector passed to the ctor does.IOException
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