Help:CirrusSearch

CirrusSearch is a newly available search engine from MediaWiki, as of June 2013. The Wikimedia Foundation migrated to CirrusSearch from MWSearch in 2014, because CirrusSearch features key improvements.

This page describes the features that are new or different compared to Help:Searching (MWSearch, still used in the field).

Frequently asked questions
If your question is not answered here, feel free to ask on the talk page and someone will answer it for you.

What's improved?
The new search engine features four main improvements over the old search engine, namely:


 * Faster updates to the search indexes: changes to articles are reflected in search results much more quickly.
 * Search index for templates: Template wordings and subtemplate naming are attributed at each page.
 * Better support for searching in different languages.
 * Regular expression searches.

Updates
Updates to the search index will (usually) occur in near real time. So you can successfully Search the change as soon as you save the page. (A null edit will force an update.)

A template change will update in a few minutes all the pages where its transclusion has changed. (The templates changes use the job queue, so performance may vary.)

Search suggestions
Search suggestions are the page names that drop down from the search box while you are typing. They are sorted by the number of incoming links.

Starting with the tilde character ~ disables search suggestions, and you will always end up on the search results page.

Search suggestions will automatically include the accented characters or the characters with diacritical markings. These are folded into there ASCII look-alikes automatically, and are turned on for English text.

Full text search
A "full text search" is an "indexed search". All pages are stored in the wiki database, and all the words in them are stored in the search database, which is an index to the full text of the wiki. Every word is indexed to the list of pages where it is found. A search can be as fast as pulling a single-record. Furthermore, the index is updated within seconds of the change.

There are actually many indexes on the "full text" of the wiki to facilitate all the searches needed. The end-user query is optimized to run the internal series of searches on them and the post-processing of those. Various search parameters advantage particular indexes, and CirrusSearch syntax advantage post processing. The resulting titles are weighted by relevance, and then processed 20 at a time: snippets are garnered, and the search results page formatted into HTML with search terms highlighted in bold text.

Templates are now indexed. If the transcluded words of a template change, then all the pages that transclude it are updated. Not just visible words, but also subtemplates are indexed per page using them. Documents stored in the Media namespace are now indexed. Thousands of formats are allowed.

Stemming
There is support for dozens of languages, but all languages are wanted.

There is a list of currently supported languages at [http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/analysis-lang-analyzer.html elasticsearch.org]; see their [http://www.elasticsearch.org/contributing-to-elasticsearch/ documentation on contributing] to submit requests or patches.

Filters (intitle:, incategory: and linksto:)


We've tightened up the syntax around these quite a bit.


 * intitle:foo
 * Find articles whose title contains foo. Stemming is enabled for foo.
 * intitle:"fine line"
 * Find articles whose title contains fine then line. Stemming is enabled. Matches The finest (lines) but not The finest ever lines.
 * intitle:foo bar
 * Find articles whose title contains foo and whose title or text contains bar.
 * -intitle:foo bar


 * Find articles whose title does not contain foo and whose title or text contains bar.
 * intitle: foo bar
 * Syntax error, devolves into searching for articles whose title or text contains intitle:, foo, and bar.
 * incategory:Music
 * Find articles that are in Category:Music
 * incategory:"music history"
 * Find articles that are in Category:Music_history


 * incategory:"musicals" incategory:"1920"
 * Find articles that are in both Category:Musicals and Category:1920
 * incategory:Felis_silvestris_catus|Dogs
 * Find articles that are either in category:Felis_silvestris_catus or in Category:Dogs
 * -incategory:"musicals" incategory:"1920"
 * Find articles that are not in Category:Musicals but are in Category:1920
 * cow*
 * Find articles whose title or text contains words that start with cow
 * linksto:Help:CirrusSearch
 * find articles that link to a page
 * -linksto:Help:CirrusSearch CirrusSearch
 * find articles that mention CirrusSearch but do not link to the page Help:CirrusSearch

prefix:
The prefix: syntax in its current form is relied upon for a great deal of functionality so it's been recreated as exactly as possible.

Note that the old rule of having to put prefix: at the end of the query still applies.

morelike:
Find articles about stinging insects. Find templates about regex searching for template usage on the wiki.
 * Find articles whose text is most similar to the text of the given articles.
 * Find articles whose text is most similar to the text of the given articles.

The  query works by choosing a set of words in the input articles and run a query with the chosen words. You can tune the way it works by adding the following parameters to the search results URL: These settings can be made persistent by overriding  in Help:System message.
 * : Minimum number of documents (per shard) that need a term for it to be considered.
 * : Maximum number of documents (per shard) that have a term for it to be considered.
 * : Maximum number of terms to be considered.
 * : Minimum number of times the term appears in the input to doc to be considered. For small fields this value should be 1.
 * : Minimal length of a term to be considered. Defaults to 0.
 * : The maximum word length above which words will be ignored. Defaults to unbounded (0).
 * (comma separated list of values): These are the fields to use. Allowed fields are,  ,  ,  ,   and.
 * ( | ): use only the field data. Defaults to : the system will extract the content of the   field to build the query.
 * : The percentage of terms to match on. Defaults to 0.3 (30 percent).
 * Example:

Namespace
A search-domain filter consisting of one namespace can be specified at the beginning of a search. Two or more namespaces may be set at the search results page, Special:Search, in the Advanced dialog. This can be set for the search, or as the default search domain.

Enter a namespace name, or enter, or enter a colon    for mainspace.

Namespace aliases are accepted.

For the File namespace,  is accepted.

You cannot use an interwiki prefix as a namespace to search other projects.

Did you mean
"Did you mean" suggestions are designed to notice if you misspell an uncommon phrase that happens to be an article title. If so, they'll let you know. They also seem to suggest more things than they ought to sometimes.

Prefer phrase matches
If you don't have too much special syntax in your query we'll give perfect phrase matches a boost. I'm being intentionally vague because I'm not sure exactly what "too much special syntax" should be. Right now if you add any explicit phrases to your search we'll turn off this feature.

Fuzzy search
Putting a ~ after a search term (but not double quotes) activates fuzzy search. You can also put a number from 0 to 1 to control the "fuzziness" fraction, e.g. nigtmare~.9 or lighnin~.1 or lighnin~0.1. Closer to one is less fuzzy.

Phrase search and proximity
Surrounding some words with quotes declares that you are searching for those words close together. You can add a ~ and then a number after the second quote to control just how close you mean. The default "closeness" is zero. One means one extra word allowed, and so on. For more than two words in the phrase, the closeness equals the total number of extra words, provided that all the words are also in order left to right.

For the closeness value of words given in right to left order, count and discard all the extra words, then add twice the the total count of remaining words minus one (in other words, add twice the number of segments). For the full proximity algorithm, see Elastic Search.

An explicit AND is required between two phrases because of the "inner" quotation marks.

Quotes and exact matches
Quotes turn on exact term matches. You can add a ~ to the quote to go back to the more aggressive matcher you know and love.

prefer-recent:
You can give recently edited articles a boost in the search results by adding "prefer-recent:" to the beginning of your search. By default this will scale 60% of the score exponentially with the time since the last edit, with a half life of 160 days. This can be modified like this: "prefer-recent:,". proportion_of_score_to_scale must be a number between 0 and 1 inclusive. half_life_in_days must be greater than 0 but allows decimal points. This number works pretty well if very small. I've tested it around .0001, which is 8.64 seconds.

This will eventually be on by default for Wikinews, but there is no reason why you can't activate it in any of your searches.

hastemplate:
You can find pages that use a certain template by adding the filter  to the search. We provide for the usual "syntactic sugar" of template calls. This means the lenient pagename and fullpagename capitalization works, and the main namespace abbreviation, ":" works. For example to find which pages transclude Quality image the full search (in all your preferred namespaces) can be: , and for that same template name in the main namespace, this works. You can omit the quotes if the template title does not contain a space. will filter pages that do not contain that template.

For wikitext that calls a template directly, you can use insource:, but hastemplate: searches the "post-expansion inclusion", so hastemplate: can find a template acting only temporarily as a "secondary template" or "meta-template", which are seen in neither the source nor content, ( but only included as a helper to any other template producing the final content). All content from a template is now reflected in search results is still the relevant philosophy here.

boost-templates:
You can boost pages' scores based on what templates they contain. This can be done directly in the search via  or you can set the default for all searches via the new   message. replaces the contents of  if the former is specified. The syntax is a bit funky but was chosen for simplicity. Some examples:


 * Find files in the China category sorting quality images first.
 * Find files in the China category sorting quality images first.


 * Find files in the China category sorting quality images first and low quality images last.
 * Find files in the China category sorting quality images first and low quality images last.


 * Find files about popcorn sorting quality images first and low quality images last. Remember that through the use of the  message this can be reduced to just.
 * Find files about popcorn sorting quality images first and low quality images last. Remember that through the use of the  message this can be reduced to just.

Don't try to add decimal points to the percentages. They don't work and search scoring is such that they are unlikely to matter much.

A word of warning about : if you add really really big or small percentages they can poison the full text scoring. Think, for example, if enwiki boosted featured articles by a million percent. Then searches for terms mentioned in featured articles would find the featured articles before exact title matches of the terms. Phrase matching would be similarly blown away so a search like  would find a featured article with those words scattered throughout it instead of the article for Brave New World.

Sorry for the inconsistent  in the name. Sorry again but the quotes are required on this one. Sorry also for the funky syntax. Sorry we don't try to emulate the template transclusion syntax like we do with.

insource:
This can pick up template arguments, URLs, links, html, etc. It has two forms, one is an indexed search, and the other is regex based.

Tip: Instead of running a bare insource:/regexp/, these return much much faster when you limit the regexp search-domain to the results of one or more index-based searches. An "exact string" regexp search is a basic search; it will simply "quote" the entire regexp, or "backslash-escape" all non-alphanumeric characters in the string. All regexp searches also require that the user develop a simple filter to generate the search domain for the regex engine to search:

The last example works from a link on a page, but { {FULLPAGENAME}} doesn't function in the search box. For example
 * ' [[Special:Search/insource:/regex/ prefix:| finds the term regex'' on this page ]].

Any search with no namespace specified (or prefix specified) searches your default search domain, settable on any search-results page, i.e. settable at Special:Search. The default search domain is commonly reset by power users to All namespaces, i.e. the entire wiki, but if this occurs for a bare regexp search, then on a large wiki it will probably incur an HTML timeout before completing the search.

A regex search actually scours each page in the search domain character-by character. By contrast, an indexed search actually queries a few records from a database separately maintained from the wiki database, and provides nearly instant results. So when using using an insource:// (a regexp of any kind), consider creating one the other search terms that will limit the regex search domain as much as possible. There are many search terms that use an index and so instantly provide a more refined search domain for the /regexp/. In order of general effectiveness:


 * insource:"" with quotation marks, duplicating the regexp except without the slashes or escape characters, is ideal.
 * intitle, incategory, and linksto are excellent filters.
 * hastemplate: is a very good filter.
 * "word1 word2 word3", with or without the quotation marks, are good.
 * namespace: is practically useless, but may enable a slow regexp search to complete.

The prefix operator is especially useful with a { {FULLPAGENAME}} in a search template, a search link, or an input box, because it automatically searches any subdirectories. To develop a new regexp, or refine a complex regexp, use  on a page with a sample of the target data.

Search terms that do not increase the efficiency of a regexp search are the page-scoring operators: morelike, boost-template, and prefer-recent.

Metacharacters
This section covers how to escape the metacharacters used in rexexp searches. For the actual meaning of the metacharacters see the explanation of the syntax.

You can search for the (seemingly basic) string of characters you once saw, like "wiki-link" or perhaps "(trans[in]clusion)", or a string you want to see, like "2 + 2 = 4", or "site.org". You can do this only with a regex search, but
 * regex only search the wikitext not the rendered text, so there are some differences around the markup, and even the number of space characters must match precisely.
 * You are obligated to supply an accompanying filter.
 * You must learn how to escape regex metacharacters.

There are two ways to escape metacharacters, and they are both useful at times, and sometimes concatenated side-by-side in the escaping of a string.
 * Backslash-escape one of them \char. The insource:/regexp/ uses slashes to delimit the regexp. Giving /reg/exp/ is ambiguous, so you must write /reg\/exp/.
 * Put a string of them in double quotes "string". Because escaping a character can't hurt, you can escape any character along with any possible metacharacters in there.
 * You can't mix methods, but you can concatenate them.

Double-quotes escaping using insource:/"regexp"/ is an easy way to search for many kinds of strings, but you can't backslash-escape anything inside a double-quoted escape.
 * instead of
 * is as good as
 * But  always.
 * And .  It finds the   literally, which is not the   you probably wanted.

Backslash-escape using insource:/regexp/ allows escaping the " and / delimiters, but requires taking into account metacharacters, and escaping any:
 * To match a  delimiter character use.
 * To match a  delimiter character use.
 * The metacharacters would be.
 * The equivalent expression is.

The simplest algorithm to create the basic string-finding expression using insource:/"regexp"/, need not take metacharacters into account except for the " and / characters:
 * 1) Write   out. (The /" delimiters "/ are not shown.)
 * 2) Replace   with   (previous double-quote: stop, concatenate, quote restart).
 * 3) Replace   with   (stop, concatenate, start).
 * 4) You get , showing concatenation of the two methods.

The square-bracket notation for creating your own character-class also escapes its metacharacters. To target a literal right square bracket in your character-class pattern, it must be backslash escaped, otherwise it can be interpreted as the closing delimiter of the character-class pattern definition. The first position of a character class will also escape the right square bracket. Inside the delimiting square brackets of a character class, the dash character also has special meaning (range) but can it too can be included literally in the class the same way as the right square bracket can. For example both of these patterns target character that is either a dash or a right square bracket or a dot:  or.

For general examples using metacharacters
 * matches "2 + 2 = 4", with zero spaces between the characters.
 * match with zero or one space in between. The equals = sign is not a metacharacter, but the plus + sign is.

There are some notable differences from standard regex metacharacters:
 * The dot . metacharacter stands for any character including a newline, so .* matches across lines.
 * The number # sign means something, and must be escaped.
 * The ^ and $ are not needed. Like "grep" (global per line, regular expression, print each line), each insource:// is a "global per document, regular expression, search-results-list each document" per document.
 * support a multi-digit numeric range like [0-9] does, but without regard to the number of character positions, or the range in each position, so <9-10> works, and even <1-111> works.

Advanced example
For example, using metacharacters to find the usage of a template called Val having, inside the template call, an unnamed parameter containing a possibly signed, three to four digit number, possibly surrounded by space characters, AND on the same page, inside a template Val call, a named argument "fmt=commas" having any allowable spaces around it, (it could be the same template call, or a separate one):



It is fast because it uses two filters so that every page the regexp crawls has the highest possible potential. Assuming your search domain is set to ALL, it searches the entire wiki, because it offers no namespace or prefix.

Auxiliary text
Cirrus considers some text in the page to be "auxiliary" to what the page is actually about. Examples include table contents, image captions, and "This article is about the XYZ. For ZYX see ZYX" style links. You can also mark article text as auxiliary by adding the  class to the html element containing the text.

Auxiliary text is worth less than the rest of the article text and it is in the snippet only if there are no main article snippets matching the search.

Lead text
Cirrus assumes that non-auxiliary text that is between the top of the page and the first heading is the "lead in" paragraph. Matches from the lead in paragraph are worth more in article ranking.

Commons search
By default when the search contains the file namespace, Cirrus will search commons as well. You can disable this behavior by adding  to the search. If you are using a namespace prefix to select the namespace the syntax looks like. If you aren't using a namespace prefix to select the namespace then the syntax looks like.