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| <title>Class FieldCacheTermsFilter |
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| <article class="content wrap" id="_content" data-uid="Lucene.Net.Search.FieldCacheTermsFilter"> |
| |
| |
| <h1 id="Lucene_Net_Search_FieldCacheTermsFilter" data-uid="Lucene.Net.Search.FieldCacheTermsFilter" class="text-break">Class FieldCacheTermsFilter |
| </h1> |
| <div class="markdown level0 summary"><p>A <a class="xref" href="Lucene.Net.Search.Filter.html">Filter</a> that only accepts documents whose single |
| term value in the specified field is contained in the |
| provided set of allowed terms.</p> |
| <p> |
| |
| <p>This is the same functionality as TermsFilter (from |
| queries/), except this filter requires that the |
| field contains only a single term for all documents. |
| Because of drastically different implementations, they |
| also have different performance characteristics, as |
| described below.</p> |
| <p> |
| |
| <p>The first invocation of this filter on a given field will |
| be slower, since a <a class="xref" href="Lucene.Net.Index.SortedDocValues.html">SortedDocValues</a> must be |
| created. Subsequent invocations using the same field |
| will re-use this cache. However, as with all |
| functionality based on <a class="xref" href="Lucene.Net.Search.IFieldCache.html">IFieldCache</a>, persistent RAM |
| is consumed to hold the cache, and is not freed until the |
| <a class="xref" href="Lucene.Net.Index.IndexReader.html">IndexReader</a> is disposed. In contrast, TermsFilter |
| has no persistent RAM consumption.</p> |
| <p> |
| |
| <p>With each search, this filter translates the specified |
| set of <a class="xref" href="Lucene.Net.Index.Terms.html">Terms</a> into a private <a class="xref" href="Lucene.Net.Util.FixedBitSet.html">FixedBitSet</a> keyed by |
| term number per unique <a class="xref" href="Lucene.Net.Index.IndexReader.html">IndexReader</a> (normally one |
| reader per segment). Then, during matching, the term |
| number for each docID is retrieved from the cache and |
| then checked for inclusion using the <a class="xref" href="Lucene.Net.Util.FixedBitSet.html">FixedBitSet</a>. |
| Since all testing is done using RAM resident data |
| structures, performance should be very fast, most likely |
| fast enough to not require further caching of the |
| <a class="xref" href="Lucene.Net.Search.DocIdSet.html">DocIdSet</a> for each possible combination of terms. |
| However, because docIDs are simply scanned linearly, an |
| index with a great many small documents may find this |
| linear scan too costly.</p> |
| <p> |
| |
| <p>In contrast, TermsFilter builds up a <a class="xref" href="Lucene.Net.Util.FixedBitSet.html">FixedBitSet</a>, |
| keyed by docID, every time it's created, by enumerating |
| through all matching docs using <a class="xref" href="Lucene.Net.Index.DocsEnum.html">DocsEnum</a> to seek |
| and scan through each term's docID list. While there is |
| no linear scan of all docIDs, besides the allocation of |
| the underlying array in the <a class="xref" href="Lucene.Net.Util.FixedBitSet.html">FixedBitSet</a>, this |
| approach requires a number of "disk seeks" in proportion |
| to the number of terms, which can be exceptionally costly |
| when there are cache misses in the OS's IO cache.</p> |
| <p> |
| |
| <p>Generally, this filter will be slower on the first |
| invocation for a given field, but subsequent invocations, |
| even if you change the allowed set of <a class="xref" href="Lucene.Net.Index.Terms.html">Terms</a>, should be |
| faster than TermsFilter, especially as the number of |
| <a class="xref" href="Lucene.Net.Index.Terms.html">Terms</a> being matched increases. If you are matching only |
| a very small number of terms, and those terms in turn |
| match a very small number of documents, TermsFilter may |
| perform faster.</p> |
| <p> |
| |
| <p>Which filter is best is very application dependent.</p> |
| </div> |
| <div class="markdown level0 conceptual"></div> |
| <div class="inheritance"> |
| <h5>Inheritance</h5> |
| <div class="level0"><span class="xref">System.Object</span></div> |
| <div class="level1"><a class="xref" href="Lucene.Net.Search.Filter.html">Filter</a></div> |
| <div class="level2"><span class="xref">FieldCacheTermsFilter</span></div> |
| </div> |
| <div class="inheritedMembers"> |
| <h5>Inherited Members</h5> |
| <div> |
| <a class="xref" href="Lucene.Net.Search.Filter.html#Lucene_Net_Search_Filter_NewAnonymous_System_Func_Lucene_Net_Index_AtomicReaderContext_Lucene_Net_Util_IBits_Lucene_Net_Search_DocIdSet__">Filter.NewAnonymous(Func<AtomicReaderContext, IBits, DocIdSet>)</a> |
| </div> |
| <div> |
| <span class="xref">System.Object.Equals(System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.Equals(System.Object, System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.GetHashCode()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.GetType()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.MemberwiseClone()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.ReferenceEquals(System.Object, System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.ToString()</span> |
| </div> |
| </div> |
| <h6><strong>Namespace</strong>: <a class="xref" href="Lucene.Net.Search.html">Lucene.Net.Search</a></h6> |
| <h6><strong>Assembly</strong>: Lucene.Net.dll</h6> |
| <h5 id="Lucene_Net_Search_FieldCacheTermsFilter_syntax">Syntax</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public class FieldCacheTermsFilter : Filter</code></pre> |
| </div> |
| <h3 id="constructors">Constructors |
| </h3> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00010/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_FieldCacheTermsFilter__ctor_System_String_Lucene_Net_Util_BytesRef___.md&value=---%0Auid%3A%20Lucene.Net.Search.FieldCacheTermsFilter.%23ctor(System.String%2CLucene.Net.Util.BytesRef%5B%5D)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/release/Lucene.Net_4_8_0_beta00010/src/Lucene.Net/Search/FieldCacheTermsFilter.cs/#L101">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_FieldCacheTermsFilter__ctor_" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.#ctor*"></a> |
| <h4 id="Lucene_Net_Search_FieldCacheTermsFilter__ctor_System_String_Lucene_Net_Util_BytesRef___" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.#ctor(System.String,Lucene.Net.Util.BytesRef[])">FieldCacheTermsFilter(String, BytesRef[])</h4> |
| <div class="markdown level1 summary"></div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public FieldCacheTermsFilter(string field, params BytesRef[] terms)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.String</span></td> |
| <td><span class="parametername">field</span></td> |
| <td></td> |
| </tr> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Util.BytesRef.html">BytesRef</a>[]</td> |
| <td><span class="parametername">terms</span></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00010/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_FieldCacheTermsFilter__ctor_System_String_System_String___.md&value=---%0Auid%3A%20Lucene.Net.Search.FieldCacheTermsFilter.%23ctor(System.String%2CSystem.String%5B%5D)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/release/Lucene.Net_4_8_0_beta00010/src/Lucene.Net/Search/FieldCacheTermsFilter.cs/#L107">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_FieldCacheTermsFilter__ctor_" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.#ctor*"></a> |
| <h4 id="Lucene_Net_Search_FieldCacheTermsFilter__ctor_System_String_System_String___" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.#ctor(System.String,System.String[])">FieldCacheTermsFilter(String, String[])</h4> |
| <div class="markdown level1 summary"></div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public FieldCacheTermsFilter(string field, params string[] terms)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.String</span></td> |
| <td><span class="parametername">field</span></td> |
| <td></td> |
| </tr> |
| <tr> |
| <td><span class="xref">System.String</span>[]</td> |
| <td><span class="parametername">terms</span></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| <h3 id="properties">Properties |
| </h3> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00010/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_FieldCacheTermsFilter_FieldCache.md&value=---%0Auid%3A%20Lucene.Net.Search.FieldCacheTermsFilter.FieldCache%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/release/Lucene.Net_4_8_0_beta00010/src/Lucene.Net/Search/FieldCacheTermsFilter.cs/#L117">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_FieldCacheTermsFilter_FieldCache_" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.FieldCache*"></a> |
| <h4 id="Lucene_Net_Search_FieldCacheTermsFilter_FieldCache" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.FieldCache">FieldCache</h4> |
| <div class="markdown level1 summary"></div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public virtual IFieldCache FieldCache { get; }</code></pre> |
| </div> |
| <h5 class="propertyValue">Property Value</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.IFieldCache.html">IFieldCache</a></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| <h3 id="methods">Methods |
| </h3> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00010/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_FieldCacheTermsFilter_GetDocIdSet_Lucene_Net_Index_AtomicReaderContext_Lucene_Net_Util_IBits_.md&value=---%0Auid%3A%20Lucene.Net.Search.FieldCacheTermsFilter.GetDocIdSet(Lucene.Net.Index.AtomicReaderContext%2CLucene.Net.Util.IBits)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/release/Lucene.Net_4_8_0_beta00010/src/Lucene.Net/Search/FieldCacheTermsFilter.cs/#L119">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_FieldCacheTermsFilter_GetDocIdSet_" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.GetDocIdSet*"></a> |
| <h4 id="Lucene_Net_Search_FieldCacheTermsFilter_GetDocIdSet_Lucene_Net_Index_AtomicReaderContext_Lucene_Net_Util_IBits_" data-uid="Lucene.Net.Search.FieldCacheTermsFilter.GetDocIdSet(Lucene.Net.Index.AtomicReaderContext,Lucene.Net.Util.IBits)">GetDocIdSet(AtomicReaderContext, IBits)</h4> |
| <div class="markdown level1 summary"></div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public override DocIdSet GetDocIdSet(AtomicReaderContext context, IBits acceptDocs)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Index.AtomicReaderContext.html">AtomicReaderContext</a></td> |
| <td><span class="parametername">context</span></td> |
| <td></td> |
| </tr> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Util.IBits.html">IBits</a></td> |
| <td><span class="parametername">acceptDocs</span></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.DocIdSet.html">DocIdSet</a></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="overrides">Overrides</h5> |
| <div><a class="xref" href="Lucene.Net.Search.Filter.html#Lucene_Net_Search_Filter_GetDocIdSet_Lucene_Net_Index_AtomicReaderContext_Lucene_Net_Util_IBits_">Filter.GetDocIdSet(AtomicReaderContext, IBits)</a></div> |
| </article> |
| </div> |
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