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Subject cvs commit: jakarta-lucene/xdocs queryparsersyntax.xml
Date Wed, 15 May 2002 13:51:50 GMT
carlson     02/05/15 06:51:50

  Added:       xdocs    queryparsersyntax.xml
  Adding Query Parser Syntax to give people a better idea of what Lucene can do and does "out
of the box".
  Revision  Changes    Path
  1.1                  jakarta-lucene/xdocs/queryparsersyntax.xml
  Index: queryparsersyntax.xml
  <?xml version="1.0"?>
          <author email="">Peter Carlson</author>
              Query Parser Syntax - Jakarta Lucene 
          <section name="Overview">
              <p>Although Lucene provides the ability to create your own query's though
its API, it also provides a rich query language through the QueryParser.</p>
              <p>This page provides syntax of Lucene's Query Parser, a lexer which interprets
a string into a Lucene Query using JavaCC.</p>
          <section name="Terms">
          <p>A query is broken up into terms and operators. There are two types of terms:
Single Terms and Phrases.</p>
          <p>A Single Term is a single word such as "test" or "hello".</p>
          <p>A Phrase is a group of words surrounded by double quotes such as "hello
          <p>Multiple terms can be combined together with Boolean operators to form
a more complex query (see below).</p>
          <section name="Fields">
          <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>
          <p>You can search any field by typing the field name followed by a colon ":"
and then the term you are looking for. </p>
          <p>As an example, let's assume a Lucene index contains two fields, title and
text and text is the default field. 
          If you want to find the document entitled "The Right Way" which contains the text
"don't go this way", you can enter: </p>
          <source>title:"The Right Way" AND text:go</source>
          <source>title:"Do it right" AND right</source>
          <p>Since text is the default field, the field indicator is not required.</p>
          <p>Note: The field is only valid for the term that it directly precedes, so
the query</p>
          <source>title:Do it right</source>
          <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>
          <section name="Term Modifiers">
          <p>Lucene supports modifying query terms to provide a wide range of searching
          <subsection name="Wildcard Searches">
          <p>Lucene supports single and multiple character wildcard searches.</p>
          <p>To perform a single character wildcard search use the "?" symbol.</p>
          <p>To perform a multiple character wildcard search use the "*" symbol.</p>
          <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
          <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>
          <p>You can also use the wildcard searches in the middle of a term.</p>
          <p>Note: You cannot use a * or ? symbol as the first character of a search.</p>
          <subsection name="Fuzzy Searches">
          <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 term.
For example to search for a term similar in spelling to "roam" use the fuzzy search: </p>
          <p>This search will find terms like foam and roams</p>
          <p>Note:Terms found by the fuzzy search will automatically get a boost factor
of 0.2</p>
          <subsection name="Boosting a Term">
          <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>
          <p>Boosting allows you to control the relevance of a document by boosting
its term. For example, if you are searching for</p>
          <source>IBM Microsoft</source>
          <p>and you want the term "IBM" to be more relevant boost it using the ^ symbol
along with the boost factor next to the term. You would type:</p>
          <source>IBM^4 Microsoft</source>
          <p>This will make documents with the term IBM appear more relevant. You can
also boost Phrase Terms as in the example: </p>
          <source>"Microsoft Word"^4 "Microsoft Excel"</source>
          <p>By default, the boost factor is 1.</p>
          <section name="Boolean operators">
          <p>Boolean operators allow terms to be combined through logic operators.
          Lucene supports AND, "+", OR, NOT and "-" as Boolean operators(Note: Boolean operators
must be ALL CAPS).</p>
          <subsection name="OR">
          <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. 
          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.
          For example to search for documents that contain either "Microsoft Word" or just
"Microsoft": </p>
          <source>"Microsoft Word" Microsoft</source>
          <source>"Microsoft Word" OR Microsoft</source>
          <subsection name="AND">
          <p>The AND operator matches documents where both terms exist anywhere in the
text of a single document. 
          This is equivalent to an intersection using sets.
          For example to search for documents that contain "Microsoft Word" and "Microsoft
Excel": </p>
          <source>"Microsoft Word" AND "Microsoft Excel"</source>
          <subsection name="+">
          <p>The "+" or required operator requires that the term after the "+" symbol
exist somewhere in a the field of a single document. For example, to search for documents
that contain jakarta or lucene:</p>
          <source>+jakarta apache</source>
          <subsection name="NOT">
          <p>The NOT operator excludes documents that contain the term after NOT.
          This is equivalent to a difference using sets.
          For example to search for documents that contain "Microsoft Word" but not "Microsoft
Excel": </p>
          <source>"Microsoft Word" NOT "Microsoft Excel"</source>
          <subsection name="-">
          <p>The "-" or prohibit operator excludes documents that contain the term after
the "-" symbol. For example to search for documents that contain "Microsoft Word" but not
"Microsoft Excel": </p>
          <source>"Microsoft Word" -"Microsoft Excel"</source>
          <section name="Grouping">
          <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.
          For example, to search for either "jakarta" or "apache" and "website":</p>
          <source>(jakarta OR apache) AND website</source>
          <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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