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# Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
title: "Vespa Query Language - YQL"
---
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<p>
Vespa accepts unstructured human input and structured
queries for application logic separately, then combines them into a single data
structure for executing on the search nodes. Human input is parsed heuristically,
while application queries are formulated in YQL.
Storing the YQL query in query profiles allows for simple URLs executing complex queries.
</p><p>
Vespa search queries are not database queries.
The basic assumption is ideally a single document should be returned,
and that should be an optimal answer to the query.
Therefore a query with e.g. no terms does not return
all documents, it is an error. A query with only a negative condition,
e.g. <em>field not contains "term"</em> is also not possible, as the base state is not
filtering away from the total corpus, but matching from an as small as possible subset.
This has led YQL in Vespa to return errors for many technically valid YQL queries
to avoid confusing search results.
</p>
<h2 id="yql-101">YQL 101</h2>
<p>
A simple search URL looks like:
<pre>
http://myhost.mydomain.com:8080/search/?yql=select%20%2A%20from%20sources%20%2A%20where%20text%20contains%20%22blues%22%3B
</pre>
In other words, <em>yql</em> contains:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20text%20contains%20%22blues%22%3B
</pre>
This is a search for all documents where the field named <em>text</em> contains the word <em>blues</em>.
The match type is determined by the <a href="reference/search-definitions-reference.html">search definition</a>.
</p><p>
Note that the terminating semicolon must be URL-quoted.
</p>
<h2 id="select-statement">SELECT</h2>
<p>
SELECT is the list of requested <a href="search-definitions.html#indexing">summary fields</a>
(a field with the "summary" index attribute).
Vespa will hide other fields in the matching documents.
<pre class="urlunencode" oncopy="">
select%20price,isbn%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%3B
</pre>
The above explicitly requests the fields "price" and "isbn" (from all sources).
The matching documents may contain other fields, but they will not be shown.
To request all fields, use an asterisk as field selection:
<pre class="urlunencode" oncopy="">
select%20*%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%3B
</pre>
The above will show all fields for the fetched documents.
No overriding of normal Vespa document summary fetching will take place.
</p>
<h2 id="from-sources">FROM SOURCES</h2>
<p>
FROM specifies which document sources to search,
it is handled in a similar way to Vespa's "sources" parameter. Example:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20music%20where%20title%20contains%20%22madonna%22%3B
</pre>
searches in the source "music" for the documents matching the "where" filter expression.
</p><p>
Searching in all sources, done by using
<code>select … from <strong>sources *</strong> where …</code>,
while searching in a set of sources is done with
<code>select … from <strong>sources source1, source2</strong> where …</code>
and searching a single source is done by
<code>select … from <strong>source1</strong> where …</code>
</p><p>
In other words, the "sources" keyword is used for querying all sources
(and then in conjunction with an asterisk), or when explicitly querying more than one source.
If only a single source is requested, the "sources" keyword is dropped.
</p>
<h2 id="contains">CONTAINS</h2>
<p>
CONTAINS is the basic building block for text search in Vespa.
How the actual search will be done, depends on the field settings in the given application.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%3B
</pre>
The field, in our case "title", must be an
<a href="search-definitions.html#indexing">indexed field or attribute</a>.
If an unknown field, or a field not configured to be somehow searchable,
is attempted searched, an error message will be generated.
</p><p>
The string which is searched for in the field will be searched for
exactly as written, though stemming, accent removal, etc may change its
contents. Whether these should take effect may controlled using annotations, as in:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%28%5B%7B%22stem%22%3A%20false%7D%5D%22madonna%22%29%3B
</pre>
Note the use of parentheses to force the correct precedence.
</p><p>
The "not contains" operation is <em>not</em> implemented,
as it would be error prone and have confusing semantics for a search platform.
</p>
<h2 id="or">OR</h2>
<p>
The OR statement accepts other OR statements, AND statements,
<a href="#userquery">userQuery</a> - and contains statements as arguments:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20or%20title%20contains%20%22saint%22%3B
</pre>
</p>
<h2 id="and">AND</h2>
<p>
The AND statement accepts other AND statements, OR statements,
<a href="#userquery">userQuery</a>, logically inverted statements - and contains statements as arguments:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20and%20title%20contains%20%22saint%22%3B
</pre>
</p>
<h2 id="and-not">AND NOT</h2>
<p>
Since Vespa does recall, as opposed to filtering, the only excluding operator in Vespa is "ANDNOT".
In YQL this is expressed as the right hand side, and only the right hand side,
argument of the AND operator may be a logically inverted expression, i.e. using the <em>!</em> operator:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20and%20%21%28title%20contains%20%22saint%22%29%3B
</pre>
</p>
<h2 id="order-by">ORDER BY</h2>
<p>
Sorting the result according to attribute vectors in Vespa is supporting using <code>order by</code>.
Adding <code>asc</code> or <code>desc</code> after the name of an attribute,
specifies sorting in ascending or descending order, respectively.
If no order is explicitly specified, ascending order is implied.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20order%20by%20price%20asc%2C%20releasedate%20desc%3B
</pre>
Sorting function, locale and strength are defined using the annotations "function", "locale" and "strength", as in:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20order%20by%20%5B%7B%22function%22%3A%20%22uca%22%2C%20%22locale%22%3A%20%22en_US%22%2C%20%22strength%22%3A%20%22IDENTICAL%22%7D%5Dother%20desc%2C%20%5B%7B%22function%22%3A%20%22lowercase%22%7D%5Dsomething%3B
</pre>
<strong>Note: </strong> <a href="reference/search-definitions-reference.html#match-phase">match-phase</a>
is enabled when sorting - refer to the <a href="reference/sorting.html">sorting reference</a>.
</p>
<h2 id="numeric-operators">Numeric Operators</h2>
<p>
The following numeric operators are available:
<em>=, &lt;, &gt;, &lt;=, &gt;=</em>
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20500%20%3E%3D%20price%3B
</pre>
In addition, <em>range(<em>field</em>, <em>lower bound</em>, <em>upper bound</em>)</em>
allows explicit matching of numeric ranges.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20range%28field%2C%200%2C%20500%29%3B
</pre>
The interval is by default a closed interval.
If the lower bound is exclusive, set the annotation "bounds" to "leftOpen".
If the upper bound is exclusive, set the same annotation to "rightOpen".
If both bounds are exclusive, set the annotation to "open". <!-- ToDo: example here! -->
</p><p>
These number operations support an extra annotation, the integer "hitLimit".
This is used for <em>capped range search</em>.
An alternative to using negative and positive values for "hitLimit"
is always using a positive number of hits
(as a negative number of hits do no not make much sense)
and combine this with either of the boolean annotations "ascending" and "descending" (but not both).
Then "[{"hitLimit": 38, "descending": true}]" would be equivalent to setting it to -38,
i.e. only populate with 38 hits and start from upper boundary, i.e. descending order.
</p><p>
Numbers must be in the signed 32-bit range. To input 64-bit signed numbers, use "L" as suffix, e.g
<pre class="urlunencode" oncopy="">
... where%20range%28field%2C%200%2C%205000000000L%29%3B
</pre>
</p>
<h2 id="grouping">Grouping</h2>
<p>
Group / aggregate results using a grouping expression:
<pre class="urlunencode" oncopy="">
select%20*%20from%20sources%20*%20where%20sddocname%20contains%20%27purchase%27%20%7C%20 all(group(customer)%20each(output(sum(price))))%3B
</pre>
<a href="grouping.html">Read more</a>.
</p>
<h2 id="pagination">Pagination</h2>
<p>
To limit the number of hits returned,
use <code>limit</code> and <code>offset</code> to specify a slice:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20limit%2031%20offset%2029%3B
</pre>
The above will return two hits (if there sufficiently many hits matching the query),
skipping the 29 first documents.
</p><p>
<code>paged</code> and <code>next</code> is not supported.
</p>
<h2 id="timeout">TIMEOUT</h2>
<p>
Set query timeout in milliseconds using <code>timeout</code>:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20contains%20%22madonna%22%20timeout%2070%3B
</pre>
Only literal numbers are allowed, e.g. setting another unit is not supported.
</p>
<h2 id="regex">Regular expressions</h2>
<p>
Limited support for using regular expressions for searching is provided.
By replacing <code>contains</code> with <code>matches</code>, vespa will do a regex search instead.
This example becomes a substring search:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20matches%20%22madonna%22%3B
</pre>
This example matches both <code>madonna</code>, <code>madona</code> and with any number of <code>n</code>s:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20matches%20%22mado%5Bn%5D%2Ba%22%3B
</pre>
Do note that you need to <strong>url encode</strong> these when using http.
The above will then look like this:
<pre oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20matches%20%22mado%5Bn%5D%2Ba%22%3B
</pre>
Here you match any string starting with <code>mad</code>:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20title%20matches%20%22^mad%22%3B
</pre>
Vespa supports regular expressions with
<a href="http://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Extended_Regular_Expressions">posix extended syntax</a>
with the limitation that it is <strong>case insensitive</strong>.
</p><p>
<strong>Note:</strong> Only <a href="reference/search-definitions-reference.html#attribute">attribute</a>
fields in <a href="reference/services-content.html#document">documents</a> that have <code>mode="index"</code> are supported.
It is also not optimized.
Having a prefix using the <code>^</code> will be faster than not having one.
</p>
<h2 id="search-specific-operators">Search specific operators</h2>
<p>
The right hand side argument of the contains operator is either a string literal, or a phrase.
YQL has no native definition of e.g. phrase matching.
Here the Vespa integration uses a function:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20text%20contains%20phrase%28%22st%22%2C%20%22louis%22%2C%20%22blues%22%29%3B
</pre>
Other Vespa specific search operators, like <a href="#wand">wand</a>, is expressed using functions as well.
</p><p>
It may be necessary to pass along extra information about a search term,
for instance when specifying a term should not be stemmed before matching.
This is done by using YQL annotations:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20text%20contains%20%28%5B%7B%22stem%22%3A%20false%7D%5D%22blues%22%29%3B
</pre>
<p>
<h3 id="near-and-ordered-near">Near and Ordered Near</h3>
<p>
<em>near()</em> and <em>onear()</em> (ordered near) are operators which match if all
argument terms occur close to each other in the same document.
onear() additionally requires the terms in the document having the same order as
given in the function (i.e. it is a phrase allowing other words interleaved).
</p><p>
near() and onear() supports the annotation <em>distance</em> which controls
how many words are allowed to separate the argument terms.
The default value is 2.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20description%20contains%20%28%5B%20%7B%22distance%22%3A%20100%7D%20%5Donear%28%22a%22%2C%20%22b%22%29%29%3B
</pre>
</p>
<h3 id="same-element">Search within same struct element</h3>
<p>
<em>sameElement()</em> is an operator that requires the terms to match within the same struct element in an array or a map field. Example:
</p>
<pre>
...
struct person {
field first_name type string {}
field last_name type string {}
field year_of_birth type int {}
}
field persons type array&lt;person&gt; {
indexing: summary
struct-field first_name { indexing: attribute }
struct-field last_name { indexing: attribute }
struct-field year_of_birth { indexing: attribute }
}
field identities type map&lt;string, person&gt; {
indexing: summary
struct-field key { indexing: attribute }
struct-field value.first_name { indexing: attribute }
struct-field value.last_name { indexing: attribute }
struct-field value.year_of_birth { indexing: attribute }
}
...
</pre>
<p>
With normal <em>AND</em> the query <code>persons.first_name AND persons.last_name</code> will normally not give you what you want.
It will match if a document has a <em>persons</em> element with a matching <em>first_name</em>
<em>AND</em> any element with a matching <em>last_name</em>.
So you will get a lot of false positives since there is nothing limiting them to the same element.
However, that is what <em>sameElement</em> ensures.
</p>
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20persons%20contains%20sameElement%28first_name%20contains%20'Joe',%20last_name%20contains%20'Smith',%20year_of_birth%20%3C%201940%29%3B
</pre>
<p>
The above returns all documents containing Joe Smith born before 1940 in the <em>persons</em> array.
</p>
<p>
Searching in a map is similar to searching in an array of struct.
The difference is that you have an extra synthetic struct with the field members <em>key</em> and <em>value</em>.
The above example with the <em>identities</em> map looks like this:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20persons%20contains%20sameElement%28key%20contains%20'father',%20value.first_name%20contains%20'Joe',%20value.last_name%20contains%20'Smith',%20value.year_of_birth%20%3C%201940%29%3B
</pre>
</p>
<p>
The above returns all documents that have tagged Joe Smith born before 1940 as a 'father'.
The importance here is using the indirection of <em>key</em> and <em>value</em> to address the keys and the values of the map.
</p>
<h3 id="equiv">Term Equivalence</h3>
<p>
If two terms in the same field should give exactly the same behavior when
match, the equiv() operator behaves like a special case of "or".
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20fieldName%20contains%20equiv%28%22A%22%2C%22B%22%29%3B
</pre>
</p>
<h3 id="term-annotations">Term Annotations</h3>
<p>
Terms and phrases can be annotated to manipulate the precise behavior of the search platform.
</p>
<h4>Annotations supported by strings</h4>
<p>
These annotations are supported by the string arguments to functions like
and phrase() and near() and also the string argument to the "contains" operator.
</p>
<table class="table">
<tr><td>"nfkc": true|false</td>
<td>NFKC normalization. Default on.</td>
</tr>
<tr><td>"implicitTransforms": true|false</td>
<td>Implicit term transformations (field defaults), default on.
If implicitTransforms is active, the settings for the field in the search
definition will be honored in term transforms, e.g. if the field has stemming, this term will be stemmed.
If implicitTransforms are turned off,
the search backend will receive the term exactly as written in the initial YQL expression.
This is in other words a top level switch to turn off all other stemming,
accent removal, Unicode normalizations and so on.</td>
</tr>
<tr><td>"annotations": {"string": "string"}</td>
<td>Custom term annotations. This is by default empty.</td>
</tr>
<tr><td>"origin": {"original": "string", "offset": int, "length": int}</td>
<td>The (sub-)string which produced this term. Default unset.</td>
</tr>
<tr><td>"usePositionData": true|false</td>
<td>Use position data for ranking algorithm. Default true.
This is <em>term</em> position, not to be confused with
<a href="reference/search-api-reference.html#geographical-searches">geo searches</a></td>
</tr>
<tr><td>"stem": true|false</td>
<td>Stem this term if it is the setting for this field, default on.</td>
</tr>
<tr><td>"normalizeCase": true|false</td>
<td>Normalize casing of this term if it is the setting for this field, default on.</td>
</tr>
<tr><td>"accentDrop": true|false</td>
<td>Remove accents from this term if it is the setting for this field, default on.</td>
</tr>
<tr><td>"andSegmenting": true|false</td>
<td>Force phrase or AND operator if re-segmenting (e.g. in stemming) this
term results in multiple terms. Default is choosing from language
settings.</td>
</tr>
<tr><td>"prefix": true|false</td>
<td>Do prefix matching for this word. Default false. ("Search for
"word*".")</td>
</tr>
<tr><td>"suffix": true|false</td>
<td>Do suffix matching for this word. Default false. ("Search for
"*word".")</td>
</tr>
<tr><td>"substring": true|false</td>
<td>Do substring matching for this word if available in the index. Default
false. ("Search for "*word*".") Only supported for streaming
search.</td>
</tr>
</table>
<h4>Annotations supported by strings and functions</h4>
<p>
These annotations are supported by strings and by the functions which
are handled like leaf nodes internally in the query tree: phrase(),
near(), onear(), range(), equiv(), weightedSet(), weakAnd() and wand().
</p>
<table class="table">
<tr><td>"id": int</td>
<td>Unique ID used for e.g. connectivity.</td>
</tr>
<tr><td>"connectivity": {"id": int, "weight": double}</td>
<td>Map with the ID and weight of explicitly connectivity of this item.</td>
</tr>
<tr><td>"significance": double</td>
<td>Significance value for ranking.</td>
</tr>
<tr><td>"annotations": {"string": "string"}</td>
<td>Custom annotations. No special semantics inside the YQL layer.</td>
</tr>
<tr><td>"filter": true|false</td>
<td>Regard this term as a "filter" term. Default false.</td>
</tr>
<tr><td>"ranked": true|false</td>
<td>Include this term for ranking calculation. Default true.</td>
</tr>
<tr><td>"label": "string"</td>
<td>Label for referring to this term during ranking.</td>
</tr>
<tr><td>"weight": int</td>
<td>Term weight, used in some ranking calculations.</td>
</tr>
</table>
<h4 id="annotations-of-sub-expressions">Annotations of sub-expressions</h4>
<p>
Consider the following query:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20%28%5B%7B%22stem%22%3A%20false%7D%5D%28foo%20contains%20%22a%22%20and%20bar%20contains%20%22b%22%29%29%20or%20foo%20contains%20%28%5B%7B%22stem%22%3A%20false%7D%5D%22c%22%29%3B
</pre>
The "stem" annotation controls whether a given term should be stemmed if its
field is configured as a stemmed field (default is "true").
The "AND" operator itself has no internal API for whether its operands should be stemmed or not,
but we can still annotate as such,
because when the value of a given annotation is determined,
the expression tree is followed from the term in question and up through its ancestors.
Traversing the tree stops when a value is found (or there is nothing more to traverse).
In other words, none of the terms in this example will be stemmed.
</p><p>
How annotations behave may be easier to understand of expressing a boolean
query in the style of an S-expression:
<pre>
(AND term1 term2 (OR term3 term4) (OR term5 (AND term6 term7)))
</pre>
The annotation scopes would then be as follows, i.e. annotations on
which elements will be checked when determining the settings for a given term:
<dl>
<dt>term1</dt>
<dd>term1 itself, and the first AND.</dd>
<dt>term2</dt>
<dd>term2 itself, and the first AND.</dd>
<dt>term3</dt>
<dd>term3 itself, the first OR and the first AND.</dd>
<dt>term4</dt>
<dd>term4 itself, the first OR and the first AND.</dd>
<dt>term5</dt>
<dd>term5 itself, the second OR and the first AND.</dd>
<dt>term6</dt>
<dd>term6 itself, the second AND, the second OR and the first AND.</dd>
<dt>term7</dt>
<dd>term7 itself, the second AND, the second OR and the first AND.</dd>
</dl>
</p>
<h2 id="query-properties">Query properties</h2>
<p>
The YQL variable syntax may be used to initialize words in phrases and as single terms.
This alleviates the need for caring about quoting a term in YQL as well as URL quoting.
The term will be used <em>exactly</em> as it is in the URL.
</p><p>
As an example, look at a query with a YQL argument, and the properties
<em>animal</em> and <em>syntaxExample</em>:
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20foo%20contains%20%40animal%20and%20foo%20contains%20phrase%28%40animal%2C%20%40syntaxExample%2C%20%40animal%29%3B&amp;animal=panda&amp;syntaxExample=syntactic
</pre>
This YQL expression will then access the query properties <em>animal</em> and
<em>syntaxExample</em> and evaluate to:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20%28foo%20contains%20%22panda%22%20AND%20foo%20contains%20phrase%28%22panda%22%2C%20%22syntactic%22%2C%20%22panda%22%29%29%3B
</pre>
</p>
<h2 id="userinput">userInput()</h2>
<p>
<em>userInput()</em> is a robust way of mixing user input and a formal query.
It allows controlling whether the user input is to be stemmed, lowercased, etc,
but it also allows for controlling whether it should be treated as a raw string,
whether it should simply be segmented or parsed as a query.
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20userInput%28%40animal%29%3B&amp;animal=panda
</pre>
Here, the userInput() function will access the query property "animal",
and parse the property value as an "ALL" query, resulting in the following expression:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20default%20contains%20%22panda%22%3B
</pre>
Now, if we changed the value of "animal" without changing the rest of the expression:
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20userInput%28%40animal%29%3B&amp;animal=panda%20smokey
</pre>
The result would be:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20default%20contains%20%22panda%22%20and%20default%20contains%20%22smokey%22%3B
</pre>
Now, let's assume we want to combine multiple query properties and have a more complex expression as well:
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20range%28year%2C%201963%2C%202014%29%20and%20%28userInput%28%40animal%29%20or%20userInput%28%40teddy%29%29%3B&amp;animal=panda&amp;teddy=bear%20roosevelt
</pre>
The resulting YQL expression will be:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20range%28year%2C%201963%2C%202014%29%20and%20%28default%20contains%20%22panda%22%20or%20%28default%20contains%20%22bear%22%20and%20default%20contains%20%22roosevelt%22%29%29%3B
</pre>
Now, consider we do not want the "teddy" field to be treated as its own query segment,
it should only be segmented with the linguistic libraries to get recall.
We can do this by adding a "grammar" annotation to the userInput() call:
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20range%28year%2C%201963%2C%202014%29%20and%20%28userInput%28%40animal%29%20or%20%5B%7B%22grammar%22%3A%20%22segment%22%7D%5DuserInput%28%40teddy%29%29%3B&amp;animal=panda&amp;teddy=bear%20roosevelt
</pre>
Then, the linguistic library will split on space, and the resulting expression is:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20range%28year%2C%201963%2C%202014%29%20and%20%28default%20contains%20%22panda%22%20or%20default%20contains%20phrase%28%22bear%22%2C%20%22roosevelt%22%29%29%3B
</pre>
Instead of a variable reference, the userInput() function also accepts raw strings as arguments,
but this would obviously not be suited for parametrizing the query from a query profile.
It is mostly intended as test feature.
</p>
<h3 id="user-input-control-annotations">userInput() control annotations</h3>
<table class="table">
<thead>
<tr>
<th>Name</th><th>Default value</th><th>Values</th><th>Effect</th>
</tr>
</thead>
<tr>
<td>grammar</td>
<td><code>all</code></td>
<td><code>raw</code>, <code>segment</code> and all values accepted for the
<a href="reference/search-api-reference.html#model.type">model.type</a> argument
in the search API.
</td>
<td>How to parse the user input. "raw" will treat the user input as a
string to be matched without any processing, "segment" will do a
first pass through the linguistic libraries, while the rest of the
values will treat the string as a query to be parsed. If query parsing
fails, an error message will be returned.
</td>
</tr>
<tr>
<td>defaultIndex</td>
<td><code>default</code></td>
<td>Any searchable field in the system's search definition.</td>
<td>Same as <a
href="reference/search-api-reference.html#model.defaultIndex">model.defaultIndex</a>
in the search API. If "grammar" is set to "raw" or "segment",
this will be the field searched.
</td>
</tr>
<tr>
<td>language</td>
<td><em>Autodetect</em></td>
<td>RFC 3066 language code</td>
<td>Language setting for the linguistics treatment of this userInput() call,
also see <a
href="reference/search-api-reference.html#model.language">model.language</a> in
the search API reference.
</td>
</tr>
<tr>
<td>allowEmpty</td>
<td><code>false</code></td>
<td>Boolean true or false.</td>
<td>Whether to allow empty input for query parsing and search terms. If this
is true, a NullItem instance is inserted in the proper place in the
query tree. If "allowEmpty" is false, the query will fail if the user
provided data can not be parsed or is empty.
</td>
</tr>
</table>
<p>
In addition, other annotations, like <em>stem</em> or <em>ranked</em>, will take effect as normal.
</p>
<h4>Limitations of annotation inheritance when treating userInput() queries</h4>
<p>
The query parsing mechanism has currently certain limitations for propagating annotation,
therefore, for any value of <em>grammar</em> other than <em>raw</em> or <em>segment</em>,
only the following annotations will take effect:
<ul>
<li><code>ranked</code></li>
<li><code>filter</code></li>
<li><code>stem</code></li>
<li><code>normalizeCase</code></li>
<li><code>accentDrop</code></li>
<li><code>usePositionData</code></li>
</ul>
</p>
<h2 id="userquery">userQuery()</h2>
<p>
<em>userQuery()</em> evaluates to the parsed user query,
i.e. the HTTP API parameter named <em>query</em>
(including the <em>filter</em> part, if this is available).
The function userQuery represents where the heuristically parsed query
is to be inserted as a sub-tree into the YQL query.
In other words, this is not a string substitution,
the user query is first parsed with any of the supported grammars,
then the resulting tree is inserted into the corresponding place in the YQL query tree:
<pre>
http://myhost.mydomain.com:8080/search/?query=abc%20def%20-ghi&amp;type=all&amp;yql=select%20%2A%20from%20sources%20%2A%20where%20vendor%20contains%20%22brick%20and%20mortar%22%20AND%20price%20%3C%2050%20AND%20userQuery%28%29%3B
</pre>
Breakdown:
<table class="table">
<tr><td>query</td>
<td>abc def -ghi</td></tr>
<tr><td>type</td>
<td>all</td></tr>
<tr><td>yql</td>
<td>select * from sources * where vendor contains "brick and mortar" AND price &lt; 50 AND userQuery();</td></tr>
</table>
The above example will in other words evaluate to a query
where the numeric field <em>price</em> must have a value lower than 50,
<em>vendor</em> must match the term <em>brick and mortar</em>,
<em>and</em> the default index must contain the two terms <em>abc</em> and <em>def</em>
while <em>not</em> containing the term <em>ghi</em>.
The spaces in the vendor term will not be used to split this into several new terms by YQL.
The string specified by the search will be used.
Query transformers may convert the string at a later stage,
but it is not necessary to do anything "special" to create a search term containing arbitrary characters.
</p>
<h3 id="convert-user-queries-to-yql">Convert user queries to YQL</h3>
<p>
Run user queries through a container instance while setting
<a href="reference/search-api-reference.html#tracelevel">tracelevel</a> to 2 or higher.
The parsed query expressed as YQL will be available in the trace info.
It is also possible to do this programmatically, using the instance method
<code>com.yahoo.search.Query.yqlRepresentation()</code> in the search API of the container.
</p>
<h2 id="yql-in-query-profiles">YQL in query profiles</h2>
<p>
YQL requires quoting to be included in a URL.
Since YQL is well suited to application logic, while not being intended for end users,
a solution to this is storing the application's YQL queries into different
<a href="query-profiles.html">query profiles</a>.
To add a default query profile, add <em>search/query-profiles/default.xml</em> to the
<a href="cloudconfig/application-packages.html">application package</a>:
<pre>
&lt;query-profile id="default"&gt;
&lt;field name="yql"&gt;select * from sources * where default contains "latest" or userQuery();&lt;/field&gt;
&lt;/query-profile&gt;
</pre>
This will add <em>latest</em> as an <em>OR term</em> to all queries not having an explicit query profile parameter.
The important thing to note is how it is not necessary to URL-quote anything in the query profiles files.
They operate independently of the HTTP parsing as such.
</p>
<h2 id="rank">rank()</h2>
<p>
The first, and only the first, argument of the rank() function determines whether a document is a match,
but all arguments are used for calculating rank score.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20rank%28a%20contains%20%22A%22%2C%20b%20contains%20%22B%22%29%3B
</pre>
</p>
<h2 id="advanced-functions">Advanced functions</h2>
<p>
These advanced functions have recall behavior similar to OR, but only return a limited number of documents.
For more information on these functions take a look at
<a href="reference/advanced-search-operators.html">Advanced Search Operators</a>.
</p>
<h3>Functions operating on a single field</h3>
<p>
wand(), dotProduct() and weightedSet() model very similar operations in the search core.
The main function to use is wand().
These functions specify a weighted set in their argument
which is matched against a single field in the backend.
</p>
<h4 id="wand">wand()</h4>
<p><em>wand()</em> (aka Parallel Wand) implements the "Weak AND"/"Weighted AND" algorithm
and is used for matching the weighted set in its argument against a single weighted set field.
The best "targetNumHits" (according to the dot product score calculated) is returned from this function:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20%5B%20%7B%22scoreThreshold%22%3A%2013%2C%20%22targetNumHits%22%3A%207%7D%20%5Dwand%28description%2C%20%7B%22a%22%3A1%2C%20%22b%22%3A2%7D%29%3B
</pre>
wand() also allows numeric arguments, then the search argument is an array of arrays of length two.
In each pair, the first number is the search term, the second its weight:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20wand%28description%2C%20%5B%5B11%2C1%5D%2C%20%5B37%2C2%5D%5D%29%3B
</pre>
</p>
<h4 id="dot-product">dotProduct()</h4>
<p>
dotProduct() calculates the dot product between the weighted set
in its argument and a weighted set field in the document as its rank score contribution:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20dotProduct%28description%2C%20%7B%22a%22%3A1%2C%20%22b%22%3A2%7D%29%3B
</pre>
</p>
<h4 id="weighted-set">weightedSet()</h4>
<p>
When using <em>weightedSet()</em> to search a field,
all tokens present in the searched field will be matched against the weighted set in the query.
This means that using a weighted set to search a single-value attribute field
will have similar semantics to using a normal term to search a weighted set field.
The low-level matching information resulting from matching a document with a weighted set in the query
will contain the weights of all the matched tokens in descending order.
Each matched weight will be represented as a standard occurrence on position 0 in element 0.
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20weightedSet%28description%2C%20%7B%22a%22%3A1%2C%20%22b%22%3A2%7D%29%3B
</pre>
</p>
<h3>Functions operating across multiple fields</h3>
<h4 id="weak-and">weakAnd()</h4>
<p>
<em>weakAnd()</em> (aka Vespa Wand) also implements the "Weak AND"/"Weighted AND" algorithm,
but unlike wand(), it accepts arbitrary word matches (across arbitrary fields) as arguments.
Only a limited number of documents are returned for ranking (default is 100),
but it does not guarantee to return the best k hits.
This function can be seen as an optimized OR:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20weakAnd%28a%20contains%20%22A%22%2C%20b%20contains%20%22B%22%29%3B
</pre>
</p>
<h4>Optional Arguments</h4>
<p>
Both wand() and weakAnd() both support the annotations "scoreThreshold",
which is an integer giving the minimum rank score for hits to include, and "targetNumHits"
which is the desired number of hits to produce from the function in question:
<pre class="urlunencode" oncopy="">
select%20%2A%20from%20sources%20%2A%20where%20%5B%7B%22scoreThreshold%22%3A%2041%2C%20%22targetNumHits%22%3A%207%7D%5DweakAnd%28a%20contains%20%22A%22%2C%20b%20contains%20%22B%22%29%3B
</pre>
</p>
<h2 id="non-empty">nonEmpty()</h2>
<p>
<em>nonEmpty</em> takes as its only argument an arbitrary search expression.
It will then perform a set of checks on that expression.
If all the checks pass, the result is the same expression, otherwise the query will fail.
The checks are as follows:
<ol>
<li>No empty search term.</li>
<li>No empty operators, like phrases without terms.</li>
<li>No null markers (NullItem) from e.g. failed query parsing.</li>
</ol>
<pre class="urlunencode" oncopy="">
yql=select%20%2A%20from%20sources%20%2A%20where%20bar%20contains%20%22a%22%20and%20nonEmpty%28bar%20contains%20%22bar%22%20and%20foo%20contains%20%40foo%29&amp;foo=
</pre>
Note how "foo" is empty in this case, which will force the query to fail.
If "foo" contained a searchable term, the query would not have failed.
</p>
<h2 id="predicate">predicate()</h2>
<p>
<em>predicate()</em> is used to specify a predicate query -
see <a href="predicate-fields.html">predicate fields</a>.
It takes three arguments: the predicate field to search, a map of attributes, and a map of range attributes:
<pre class="urlunencode" oncopy="">
select%20*%20from%20sources%20*%20where%20predicate(predicate_field%2C%7B%22gender%22%3A%22Female%22%7D%2C%7B%22age%22%3A20L%7D)%3B
</pre>
Due to a quirk in YQL-parsing, one cannot specify an empty map, use the number 0 instead.
<pre class="urlunencode" oncopy="">
select%20*%20from%20sources%20*%20where%20predicate(predicate_field%2C0%2C%7B%22age%22%3A20L%7D)%3B
</pre>
</p>
<h2 id="known-issues">Known issues</h2>
<p>
<strong>Query rewriting in searcher plug-ins:</strong>
In applications where query rewriting is done using a searcher
plug-in in the container, one must annotate searchers.
The <em>yql</em> query property is handled by a searcher as well,
so if annotating the custom searcher with <em>@Before("ExternalYql")</em>
the data in the YQL query parameter will never be present.
Conversely, to ensure always getting the query defined in <em>yql</em>,
annotate with <em>@After("ExternalYql")</em>.
</p>
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