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| <h1 id="Lucene_Net_Queries" data-uid="Lucene.Net.Queries" class="text-break">Namespace Lucene.Net.Queries |
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| <div class="markdown level0 summary"><!-- |
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| <p>Filters and Queries that add to core Lucene.</p> |
| </div> |
| <div class="markdown level0 conceptual"></div> |
| <div class="markdown level0 remarks"></div> |
| <h3 id="classes">Classes |
| </h3> |
| <h4><a class="xref" href="Lucene.Net.Queries.BooleanFilter.html">BooleanFilter</a></h4> |
| <section><p>A container <span class="xref">Lucene.Net.Search.Filter</span> that allows Boolean composition of <span class="xref">Lucene.Net.Search.Filter</span>s. |
| <span class="xref">Lucene.Net.Search.Filter</span>s are allocated into one of three logical constructs; |
| SHOULD, MUST NOT, MUST |
| The results <span class="xref">Lucene.Net.Search.Filter</span> BitSet is constructed as follows: |
| SHOULD Filters are OR'd together |
| The resulting <span class="xref">Lucene.Net.Search.Filter</span> is NOT'd with the NOT <span class="xref">Lucene.Net.Search.Filter</span>s |
| The resulting <span class="xref">Lucene.Net.Search.Filter</span> is AND'd with the MUST <span class="xref">Lucene.Net.Search.Filter</span>s</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.BoostingQuery.html">BoostingQuery</a></h4> |
| <section><p>The <a class="xref" href="Lucene.Net.Queries.BoostingQuery.html">BoostingQuery</a> class can be used to effectively demote results that match a given query. |
| Unlike the "NOT" clause, this still selects documents that contain undesirable terms, |
| but reduces their overall score:</p> |
| <pre><code> Query balancedQuery = new BoostingQuery(positiveQuery, negativeQuery, 0.01f);</code></pre> |
| <p>In this scenario the positiveQuery contains the mandatory, desirable criteria which is used to |
| select all matching documents, and the negativeQuery contains the undesirable elements which |
| are simply used to lessen the scores. Documents that match the negativeQuery have their score |
| multiplied by the supplied "boost" parameter, so this should be less than 1 to achieve a |
| demoting effect</p> |
| <p>This code was originally made available here: <code>[WWW] <a href="http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2">http://marc.theaimsgroup.com/?l=lucene-user&m=108058407130459&w=2</a> </code> |
| and is documented here: <code><a href="http://wiki.apache.org/lucene-java/CommunityContributions">http://wiki.apache.org/lucene-java/CommunityContributions</a></code></p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.ChainedFilter.html">ChainedFilter</a></h4> |
| <section><p> |
| Allows multiple <span class="xref">Lucene.Net.Search.Filter</span>s to be chained. |
| Logical operations such as <strong>NOT</strong> and <strong>XOR</strong> |
| are applied between filters. One operation can be used |
| for all filters, or a specific operation can be declared |
| for each filter. |
| </p> |
| <p> |
| Order in which filters are called depends on |
| the position of the filter in the chain. It's probably |
| more efficient to place the most restrictive filters/least |
| computationally-intensive filters first. |
| </p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.CommonTermsQuery.html">CommonTermsQuery</a></h4> |
| <section><p>A query that executes high-frequency terms in a optional sub-query to prevent |
| slow queries due to "common" terms like stopwords. This query |
| builds 2 queries off the <a class="xref" href="Lucene.Net.Queries.CommonTermsQuery.html#Lucene_Net_Queries_CommonTermsQuery_Add_Lucene_Net_Index_Term_">Add(Term)</a> added terms: low-frequency |
| terms are added to a required boolean clause and high-frequency terms are |
| added to an optional boolean clause. The optional clause is only executed if |
| the required "low-frequency" clause matches. Scores produced by this query |
| will be slightly different than plain <a class="xref" href="https://lucenenet.apache.org/docs/4.8.0-beta00013/api/core/Lucene.Net.Search.BooleanQuery.html">BooleanQuery</a> scorer mainly due to |
| differences in the <a class="xref" href="https://lucenenet.apache.org/docs/4.8.0-beta00013/api/core/Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_Coord_System_Int32_System_Int32_">Coord(Int32, Int32)</a> number of leaf queries |
| in the required boolean clause. In most cases, high-frequency terms are |
| unlikely to significantly contribute to the document score unless at least |
| one of the low-frequency terms are matched. This query can improve |
| query execution times significantly if applicable. |
| <p> |
| <a class="xref" href="Lucene.Net.Queries.CommonTermsQuery.html">CommonTermsQuery</a> has several advantages over stopword filtering at |
| index or query time since a term can be "classified" based on the actual |
| document frequency in the index and can prevent slow queries even across |
| domains without specialized stopword files. |
| </p> |
| <p> |
| <strong>Note:</strong> if the query only contains high-frequency terms the query is |
| rewritten into a plain conjunction query ie. all high-frequency terms need to |
| match in order to match a document. |
| </p> |
| <p> |
| Collection initializer note: To create and populate a <a class="xref" href="Lucene.Net.Queries.CommonTermsQuery.html">CommonTermsQuery</a> |
| in a single statement, you can use the following example as a guide:</p> |
| <pre><code>var query = new CommonTermsQuery() { |
| new Term("field", "microsoft"), |
| new Term("field", "office") |
| };</code></pre> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.CustomScoreProvider.html">CustomScoreProvider</a></h4> |
| <section><p>An instance of this subclass should be returned by |
| <a class="xref" href="Lucene.Net.Queries.CustomScoreQuery.html#Lucene_Net_Queries_CustomScoreQuery_GetCustomScoreProvider_Lucene_Net_Index_AtomicReaderContext_">GetCustomScoreProvider(AtomicReaderContext)</a>, if you want |
| to modify the custom score calculation of a <a class="xref" href="Lucene.Net.Queries.CustomScoreQuery.html">CustomScoreQuery</a>. |
| <p>Since Lucene 2.9, queries operate on each segment of an index separately, |
| so the protected <a class="xref" href="Lucene.Net.Queries.CustomScoreProvider.html#Lucene_Net_Queries_CustomScoreProvider_m_context">m_context</a> field can be used to resolve doc IDs, |
| as the supplied <code>doc</code> ID is per-segment and without knowledge |
| of the <span class="xref">Lucene.Net.Index.IndexReader</span> you cannot access the document or <span class="xref">Lucene.Net.Search.IFieldCache</span>.</p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div><p>@since 2.9.2</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.CustomScoreQuery.html">CustomScoreQuery</a></h4> |
| <section><p>Query that sets document score as a programmatic function of several (sub) scores: |
| <ul><li>the score of its subQuery (any query)</li><li>(optional) the score of its <a class="xref" href="Lucene.Net.Queries.Function.FunctionQuery.html">FunctionQuery</a> (or queries).</li></ul> |
| Subclasses can modify the computation by overriding <a class="xref" href="Lucene.Net.Queries.CustomScoreQuery.html#Lucene_Net_Queries_CustomScoreQuery_GetCustomScoreProvider_Lucene_Net_Index_AtomicReaderContext_">GetCustomScoreProvider(AtomicReaderContext)</a>. |
| <p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></section> |
| <h4><a class="xref" href="Lucene.Net.Queries.FilterClause.html">FilterClause</a></h4> |
| <section><p>A <span class="xref">Lucene.Net.Search.Filter</span> that wrapped with an indication of how that filter |
| is used when composed with another filter. |
| (Follows the boolean logic in <a class="xref" href="https://lucenenet.apache.org/docs/4.8.0-beta00013/api/core/Lucene.Net.Search.BooleanClause.html">BooleanClause</a> for composition |
| of queries.)</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.TermFilter.html">TermFilter</a></h4> |
| <section><p>A filter that includes documents that match with a specific term.</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Queries.TermsFilter.html">TermsFilter</a></h4> |
| <section><p>Constructs a filter for docs matching any of the terms added to this class. |
| Unlike a RangeFilter this can be used for filtering on multiple terms that are not necessarily in |
| a sequence. An example might be a collection of primary keys from a database query result or perhaps |
| a choice of "category" labels picked by the end user. As a filter, this is much faster than the |
| equivalent query (a <a class="xref" href="https://lucenenet.apache.org/docs/4.8.0-beta00013/api/core/Lucene.Net.Search.BooleanQuery.html">BooleanQuery</a> with many "should" <a class="xref" href="https://lucenenet.apache.org/docs/4.8.0-beta00013/api/core/Lucene.Net.Search.TermQuery.html">TermQuery</a>s)</p> |
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