Restream/redmine_elasticsearch

<p>
  The query string “mini-language” is used by the Query String Query and by the q query string parameter in the search
  API.
  The query string is parsed into a series of terms and operators. A term can be a single word — quick or brown — 
  or a phrase, surrounded by double quotes — "quick brown" — which searches for all the words in the phrase, in the same
  order.
  Operators allow you to customize the search — the available options are explained below.
</p>

<h3><a id="word"><%= l('es.word') %></a></h3>

For searching a word just type a whole word:

<p class="search-phrase">computer</p>

or its part (from begining):

<p class="search-phrase">comp</p>

By default search will be performed on these fields:

<ul>
  <li>title(<%= l(:field_title) %>)</li>
  <li>description(<%= l(:field_description) %>)</li>
  <li>notes(Notes for Issue) - only for Issue</li>
</ul>

If you enable checkbox "Search titles only" then search
will be performed only fo field title(<%= l(:field_title) %>).

<h3><a id="phrase"><%= l('es.phrase') %></a></h3>

Phrase, surrounded by double quotes — "quick brown" — will search
for all the words in the phrase, in the same order.

<p class="search-phrase">"quick brown"</p>

<h3><a id="many_words"><%= l('es.many_words') %></a></h3>

For searching one of words:

<p class="search-phrase">fox brown bar</p>

For searching documents with all words you should enable "All words" checkbox.

<h3><a id="wildcards"><%= l('es.wildcards') %></a></h3>

Wildcard searches can be run on individual terms, using '?' to replace a single character, and '*'
to replace zero or more characters:

<p class="search-phrase">qu?ck bro*</p>

Be aware that wildcard queries can use an enormous amount of memory and perform very badly — just think how many terms
need to be queried to match the query string "a* b* c*".

<p>
  Warning<br/>
  Allowing a wildcard at the beginning of a word (eg "*ing") is particularly heavy, because all terms in the index need
  to be examined, just in case they match.
</p>

<h3><a id="field"><%= l('es.field') %></a></h3>
As mentioned above, the default_fields is searched for the search terms,
but it is possible to specify other fields in the query syntax:

<ul>
  <li>
    where the status field is new
    <p class="search-phrase">status:new</p>
  </li>
  <li>
    where the title field contains quick or brown
    <p class="search-phrase">title:(quick brown)</p>
  </li>
  <li>
    where the author field contains the exact phrase "john smith"
    <p class="search-phrase">author:"John Smith"</p>
  </li>
  <li>
    where any of the fields book.title, book.content or book.date contains quick or brown (note how we need
    to escape the * with a backslash):
    <p class="search-phrase">book.\*:(quick brown)</p>
  </li>
  <li>
    where the field title has no value (or is missing):
    <p class="search-phrase">_missing_:title</p>
  </li>
  <li>
    where the field title has any non-null value:
    <p class="search-phrase">_exists_:title</p>
  </li>
</ul>

<h3><a id="text-attachments"><%= l('es.attachments') %></a></h3>
<p>
  You can search issues, projects, news, documents, wiki_pages and messages by attachments.
  Here an example for searching container with attachment filename "somefile.pdf":
</p>
<p class="search-phrase">attachments.filename:somefile.pdf</p>
<a href="#attachments">List of attachment fields</a>

<h3><a id="regular_expression"><%= l('es.regular_expression') %></a></h3>

Regular expression patterns can be embedded in the query string by wrapping them in forward-slashes ("/"):

<p class="search-phrase">author:/joh?n(ath[oa]n)/</p>

The supported regular expression syntax is explained in
<a href="http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-regexp-query.html#regexp-syntax">Regular
  expression syntax</a>.

<p>
  Warning<br/>
  A query string such as the following would force Elasticsearch to visit every term in the index:
</p>

<p class="search-phrase">/.*n/</p>

Use with caution!

<h3><a id="fuzziness"><%= l('es.fuzziness') %></a></h3>

We can search for terms that are similar to, but not exactly like our search terms, using the “fuzzy” operator:

<p class="search-phrase">quikc~ brwn~ foks~</p>

This uses the Damerau-Levenshtein distance to find all terms with a maximum of two changes,
where a change is the insertion, deletion or substitution of a single character,
or transposition of two adjacent characters.

The default edit distance is 2, but an edit distance of 1 should be sufficient to catch 80% of all human misspellings.
It can be specified as:

<p class="search-phrase">quikc~1</p>

<h3><a id="proximity_searches"><%= l('es.proximity_searches') %></a></h3>

While a phrase query (eg "john smith") expects all of the terms in exactly the same order, a proximity query allows the
specified words to be further apart or in a different order. In the same way that fuzzy queries can specify a maximum
edit distance for characters in a word, a proximity search allows us to specify a maximum edit distance
of words in a phrase:

<p class="search-phrase">"fox quick"~5</p>

The closer the text in a field is to the original order specified in the query string, the more relevant that document
is considered to be. When compared to the above example query, the phrase "quick fox" would be considered more
relevant than "quick brown fox".

<h3><a id="ranges"><%= l('es.ranges') %></a></h3>

<p>
  Ranges can be specified for date, numeric or string fields. Inclusive ranges are specified with square
  brackets [min TO max] and exclusive ranges with curly brackets {min TO max}.
</p>

All days in 2013:

<p class="search-phrase">datetime:[2013-01-01 TO 2013-12-31]</p>

Numbers 1..5

<p class="search-phrase">count:[1 TO 5]</p>

Tags between alpha and omega, excluding alpha and omega:

<p class="search-phrase">tags:{alpha TO omega}</p>

Numbers from 10 upwards

<p class="search-phrase">count:[10 TO *]</p>

Dates before 2012

<p class="search-phrase">datetime:{* TO 2012-01-01}</p>

Curly and square brackets can be combined:<br/>
Numbers from 1 up to but not including 5

<p class="search-phrase">count:[1..5}</p>

Ranges with one side unbounded can use the following syntax:

<p class="search-phrase">
  age:>10<br/>
  age:>=10<br/>
  age:<10<br/>
  age:<=10
</p>

Note
To combine an upper and lower bound with the simplified syntax, you would need to join two clauses with an AND operator:

<p class="search-phrase">
  age:(>=10 AND <20)<br/>
  age:(+>=10 +<20)
</p>

<h3><a id="boosting"><%= l('es.boosting') %></a></h3>
Use the boost operator ^ to make one term more relevant than another.
For instance, if we want to find all documents about foxes, but we are especially interested in quick foxes:

<p class="search-phrase">quick^2 fox</p>

The default boost value is 1, but can be any positive floating point number. Boosts between 0 and 1 reduce relevance.
<br/>

Boosts can also be applied to phrases or to groups:
<p class="search-phrase">"john smith"^2 (foo bar)^4</p>

<h3><a id="boolean_operators"><%= l('es.boolean_operators') %></a></h3>
<p>
  By default, all terms are optional, as long as one term matches.
  A search for foo bar baz will find any document that contains one or more of foo or bar or baz.
  We have already discussed the default_operator above which allows you to force all terms to be required,
  but there are also boolean operators which can be used in the query string itself to provide more control.
</p>
<p>
  The preferred operators are + (this term must be present) and - (this term must not be present).
  All other terms are optional. For example, this query:
</p>

<p class="search-phrase">quick brown +fox -news</p>

<p>
  states that:<br/>

  fox must be present<br/>
  news must not be present<br/>
  quick and brown are optional — their presence increases the relevance
</p>

<p>
  The familiar operators AND, OR and NOT (also written &&, || and !) are also supported.
  However, the effects of these operators can be more complicated than is obvious at first glance.
  NOT takes precedence over AND, which takes precedence over OR.
  While the + and - only affect the term to the right of the operator,
  AND and OR can affect the terms to the left and right.
</p>

<h3><a id="grouping"><%= l('es.grouping') %></a></h3>
Multiple terms or clauses can be grouped together with parentheses, to form sub-queries:

<p class="search-phrase">(quick OR brown) AND fox</p>

Groups can be used to target a particular field, or to boost the result of a sub-query:

<p class="search-phrase">status:(active OR pending) title:(full text search)^2</p>

<h3><a id="reserved_characters"><%= l('es.reserved_characters') %></a></h3>

<p>
  If you need to use any of the characters which function as operators in your query itself (and not as operators),
  then you should escape them with a leading backslash. For instance, to search for (1+1)=2, you would need
  to write your query as \(1\+1\)=2.
</p>

<p>
  The reserved characters are: + - && || ! ( ) { } [ ] ^ " ~ * ? : \ /
</p>

<p>
  Failing to escape these special characters correctly could lead to a syntax error which prevents your query from
  running.
</p>

<h3><a id="empty_query"><%= l('es.empty_query') %></a></h3>

<p>
  If the query string is empty or only contains whitespaces the query string is interpreted as a no_docs_query
  and will yield an empty result set.
</p>