mirror of https://github.com/apache/lucene.git
213 lines
12 KiB
XML
213 lines
12 KiB
XML
<?xml version="1.0"?>
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<document>
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<properties>
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<author email="carlson@apache.org">Peter Carlson</author>
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<title>
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Query Parser Syntax - Jakarta Lucene
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</title>
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</properties>
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<body>
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<section name="Overview">
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<p>Although Lucene provides the ability to create your own
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queries through its API, it also provides a rich query
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language through the Query Parser.</p> <p>This page
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provides syntax of Lucene's Query Parser, a lexer which
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interprets a string into a Lucene Query using JavaCC.</p>
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<p>
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Before choosing to use the provided Query Parser, please consider the following:
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<ol>
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<li>If you are programmatically generating a query string and then
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parsing it with the query parser then you should seriously consider building
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your queries directly with the query API. In other words, the query
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parser is designed for human-entered text, not for program-generated
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text.</li>
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<li>Untokenized fields are best added directly to queries, and not
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through the query parser. If a field's values are generated programmatically
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by the application, then so should query clauses for this field.
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An analyzer, which the query parser uses, is designed to convert human-entered
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text to terms. Program-generated values, like dates, keywords, etc.,
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should be consistently program-generated.</li>
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<li>In a query form, fields which are general text should use the query
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parser. All others, such as date ranges, keywords, etc. are better added
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directly through the query API. A field with a limit set of values,
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that can be specified with a pull-down menu should not be added to a
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query string which is subsequently parsed, but rather added as a
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TermQuery clause.</li>
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</ol>
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</p>
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</section>
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<section name="Terms">
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<p>A query is broken up into terms and operators. There are two types of terms: Single Terms and Phrases.</p>
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<p>A Single Term is a single word such as "test" or "hello".</p>
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<p>A Phrase is a group of words surrounded by double quotes such as "hello dolly".</p>
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<p>Multiple terms can be combined together with Boolean operators to form a more complex query (see below).</p>
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<p>Note: The analyzer used to create the index will be used on the terms and phrases in the query string.
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So it is important to choose an analyzer that will not interfere with the terms used in the query string.</p>
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</section>
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<section name="Fields">
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<p>Lucene supports fielded data. When performing a search you can either specify a field, or use the default field. The field names and default field is implementation specific.</p>
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<p>You can search any field by typing the field name followed by a colon ":" and then the term you are looking for. </p>
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<p>As an example, let's assume a Lucene index contains two fields, title and text and text is the default field.
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If you want to find the document entitled "The Right Way" which contains the text "don't go this way", you can enter: </p>
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<source>title:"The Right Way" AND text:go</source>
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<p>or</p>
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<source>title:"Do it right" AND right</source>
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<p>Since text is the default field, the field indicator is not required.</p>
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<p>Note: The field is only valid for the term that it directly precedes, so the query</p>
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<source>title:Do it right</source>
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<p>Will only find "Do" in the title field. It will find "it" and "right" in the default field (in this case the text field). </p>
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</section>
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<section name="Term Modifiers">
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<p>Lucene supports modifying query terms to provide a wide range of searching options.</p>
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<subsection name="Wildcard Searches">
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<p>Lucene supports single and multiple character wildcard searches.</p>
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<p>To perform a single character wildcard search use the "?" symbol.</p>
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<p>To perform a multiple character wildcard search use the "*" symbol.</p>
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<p>The single character wildcard search looks for terms that match that with the single character replaced. For example, to search for "text" or "test" you can use the search:</p>
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<source>te?t</source>
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<p>Multiple character wildcard searches looks for 0 or more characters. For example, to search for test, tests or tester, you can use the search: </p>
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<source>test*</source>
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<p>You can also use the wildcard searches in the middle of a term.</p>
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<source>te*t</source>
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<p>Note: You cannot use a * or ? symbol as the first character of a search.</p>
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</subsection>
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<subsection name="Fuzzy Searches">
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<p>Lucene supports fuzzy searches based on the Levenshtein Distance, or Edit Distance algorithm. To do a fuzzy search use the tilde, "~", symbol at the end of a Single word Term. For example to search for a term similar in spelling to "roam" use the fuzzy search: </p>
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<source>roam~</source>
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<p>This search will find terms like foam and roams.</p>
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<p>Starting with Lucene 1.9 an additional (optional) parameter can specify the required similarity. The value is between 0 and 1, with a value closer to 1 only terms with a higher similarity will be matched. For example:</p>
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<source>roam~0.8</source>
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<p>The default that is used if the parameter is not given is 0.5.</p>
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</subsection>
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<subsection name="Proximity Searches">
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<p>Lucene supports finding words are a within a specific distance away. To do a proximity search use the tilde, "~", symbol at the end of a Phrase. For example to search for a "apache" and "jakarta" within 10 words of each other in a document use the search: </p>
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<source>"jakarta apache"~10</source>
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</subsection>
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<subsection name="Range Searches">
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<p>Range Queries allow one to match documents whose field(s) values
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are between the lower and upper bound specified by the Range Query.
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Range Queries can be inclusive or exclusive of the upper and lower bounds.
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Sorting is done lexicographically.</p>
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<source>mod_date:[20020101 TO 20030101]</source>
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<p>This will find documents whose mod_date fields have values between 20020101 and 20030101, inclusive.
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Note that Range Queries are not reserved for date fields. You could also use range queries with non-date fields:</p>
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<source>title:{Aida TO Carmen}</source>
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<p>This will find all documents whose titles are between Aida and Carmen, but not including Aida and Carmen.</p>
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<p>Inclusive range queries are denoted by square brackets. Exclusive range queries are denoted by
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curly brackets.</p>
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</subsection>
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<subsection name="Boosting a Term">
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<p>Lucene provides the relevance level of matching documents based on the terms found. To boost a term use the caret, "^", symbol with a boost factor (a number) at the end of the term you are searching. The higher the boost factor, the more relevant the term will be.</p>
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<p>Boosting allows you to control the relevance of a document by boosting its term. For example, if you are searching for</p>
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<source>jakarta apache</source>
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<p>and you want the term "jakarta" to be more relevant boost it using the ^ symbol along with the boost factor next to the term.
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You would type:</p>
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<source>jakarta^4 apache</source>
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<p>This will make documents with the term jakarta appear more relevant. You can also boost Phrase Terms as in the example: </p>
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<source>"jakarta apache"^4 "jakarta lucene"</source>
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<p>By default, the boost factor is 1. Although the boost factor must be positive, it can be less than 1 (e.g. 0.2)</p>
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</subsection>
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</section>
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<section name="Boolean operators">
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<p>Boolean operators allow terms to be combined through logic operators.
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Lucene supports AND, "+", OR, NOT and "-" as Boolean operators(Note: Boolean operators must be ALL CAPS).</p>
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<subsection name="OR">
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<p>The OR operator is the default conjunction operator. This means that if there is no Boolean operator between two terms, the OR operator is used.
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The OR operator links two terms and finds a matching document if either of the terms exist in a document. This is equivalent to a union using sets.
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The symbol || can be used in place of the word OR.</p>
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<p>To search for documents that contain either "jakarta apache" or just "jakarta" use the query:</p>
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<source>"jakarta apache" jakarta</source>
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<p>or</p>
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<source>"jakarta apache" OR jakarta</source>
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</subsection>
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<subsection name="AND">
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<p>The AND operator matches documents where both terms exist anywhere in the text of a single document.
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This is equivalent to an intersection using sets. The symbol && can be used in place of the word AND.</p>
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<p>To search for documents that contain "jakarta apache" and "jakarta lucene" use the query: </p>
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<source>"jakarta apache" AND "jakarta lucene"</source>
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</subsection>
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<subsection name="+">
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<p>The "+" or required operator requires that the term after the "+" symbol exist somewhere in a the field of a single document.</p>
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<p>To search for documents that must contain "jakarta" and may contain "lucene" use the query:</p>
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<source>+jakarta apache</source>
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</subsection>
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<subsection name="NOT">
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<p>The NOT operator excludes documents that contain the term after NOT.
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This is equivalent to a difference using sets. The symbol ! can be used in place of the word NOT.</p>
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<p>To search for documents that contain "jakarta apache" but not "jakarta lucene" use the query: </p>
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<source>"jakarta apache" NOT "jakarta lucene"</source>
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<p>Note: The NOT operator cannot be used with just one term. For example, the following search will return no results:</p>
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<source>NOT "jakarta apache"</source>
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</subsection>
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<subsection name="-">
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<p>The "-" or prohibit operator excludes documents that contain the term after the "-" symbol.</p>
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<p>To search for documents that contain "jakarta apache" but not "jakarta lucene" use the query: </p>
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<source>"jakarta apache" -"jakarta lucene"</source>
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</subsection>
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</section>
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<section name="Grouping">
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<p>Lucene supports using parentheses to group clauses to form sub queries. This can be very useful if you want to control the boolean logic for a query.</p>
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<p>To search for either "jakarta" or "apache" and "website" use the query:</p>
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<source>(jakarta OR apache) AND website</source>
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<p>This eliminates any confusion and makes sure you that website must exist and either term jakarta or apache may exist.</p>
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</section>
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<section name="Field Grouping">
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<p>Lucene supports using parentheses to group multiple clauses to a single field.</p>
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<p>To search for a title that contains both the word "return" and the phrase "pink panther" use the query:</p>
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<source>title:(+return +"pink panther")</source>
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</section>
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<section name="Escaping Special Characters">
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<p>Lucene supports escaping special characters that are part of the query syntax. The current list special characters are</p>
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<p>+ - && || ! ( ) { } [ ] ^ " ~ * ? : \</p>
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<p>To escape these character use the \ before the character. For example to search for (1+1):2 use the query:</p>
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<source>\(1\+1\)\:2</source>
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</section>
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</body>
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</document>
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