Справка:CirrusSearch

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Самый быстрый способ найти информацию в проектах Викимедиа — поискать её напрямую. На каждой странице есть поле «поиск».

CirrusSearch — это расширение MediaWiki, использующее Elasticsearch для предоставления расширенных возможностей поиска по сравнению с базовыми инструментами поиска в MediaWiki. Фонд Викимедиа использует CirrusSearch во всех проектах Викимедиа. Эта страница описывает возможности CirrusSearch. Если вы не нашли ответ на ваш вопрос здесь, то не стесняйтесь задать его на странице обсуждения, и кто-нибудь обязательно ответит вам.

Информацию о расширении MediaWiki можно найти по ссылке Расширение:CirrusSearch .

Об использовании в Викиданных — см. Help:Extension:WikibaseCirrusSearch .

Как это работает

Введите ключевые слова или фразы и нажмите клавишу ↵ Enter или Return на своей клавиатуре. Или нажмите на значок с лупой, кнопку «Найти» или «Перейти».

При совпадении введённого вами с заголовком страницы вы будете перенаправлены на неё. В ином случае поиск ведётся по всем страницам википроекта, а в виде его результата выдаётся список соответствующих запросу страниц либо сообщение об отсутствии таких страниц.

При нажатии на кнопку «Найти» без ввода поисковых фраз вы будете перенаправлены на страницу «Служебная:Поиск», где доступны дополнительные опции поиска (также доступно с любой страницы поисковой выдачи).

Вам может быть удобно ограничить поиск определёнными пространствами имён, например, искать только среди страниц пространства «User». Проверьте пространства имен, которые требуются для этого поиска.

Все ключевые слова, указанные ниже, чувствительны к регистру и даны в нижнем регистре.

Что улучшено?

Поисковой движок CirrusSearch включает три главных улучшения по сравнению с базовой функциональностью MediaWiki:

  • Лучшая поддержка поиска на разных языках.
  • Более быстрые обновления поискового индекса, что означает, что изменения в статьях будут отображаться в поиске намного скорее.
  • Раскрывающиеся шаблоны: всё содержание, подставляемое из шаблона, будет отображено в результатах поиска.

Как часто обновляется поисковый индекс?

There are two primary search indexes to consider:

The first is full-text search, on Special:Search. This index is updated in near real time. Изменения в страницах должны попадать в поисковый индекс через несколько минут после их внесения, но 30-минутное отставание по-прежнему считаются нормальным. Хотя правки шаблонов должны отражаться в статьях, куда эти шаблоны включены, уже спустя несколько минут, этот процесс может занимать до нескольких часов — в зависимости от количества страниц, использующих шаблон. Нулевая правка в статье позволяет обойти очередь, но в ней нет необходимости, если всё работает нормально.

The second index to consider is the fuzzy auto-complete title search. This index is updated once a day and mirrors what was found in the full-text search index at the time the index was updated. Depending on timing a new page could take two days to be found in the fuzzy title autocomplete. If this is unacceptable for a particular use case, within user search options the title completion can be changed to classic prefix search which uses the full-text search index.

Поисковые подсказки

Вводя запрос в окно поиска, вы видите выпадающий список «поисковых подсказок» — статей, названия которых начинаются с введённой вами фразы; список отсортирован, исходя из грубой оценки качества этих статей. При этом учитывается количество вики-ссылок и перенаправлений, ссылающихся на статью, размер страницы, количество внешних ссылок, количество заголовков.

Поисковые подсказки можно пропустить, и запросы будут отправляться непосредственно на страницу результатов поиска. Добавьте тильду ~ перед запросом. Пример — «~Фрида Кало». Поисковые подсказки по-прежнему появятся, но в любой момент нажатие клавиши «Ввод» приведёт вас к странице результатов поиска.

Для некоторых языков включено «сворачивание» диакритических знаков (т.е., вероятно, символы «е» и «ё» не будут различаться); детали зависят от языка.

The algorithm used to rank suggestions is described in more detail at Extension:CirrusSearch/CompletionSuggester#Ranking criteria.

Полнотекстовый поиск

«Полнотекстовый поиск» (тот, что приводит на страницу результатов) осуществляется на основании т.н. «поискового индекса». Все вики-страницы хранятся в базе данных вики-сайта, и все слова в них включены в специальную поисковую базу данных, содержащую указатели на полные тексты статей. Каждое видимое слово индексируется в список страниц, где оно встречается, поэтому поиск по слову в тексте происходит так же быстро, как поиск конкретного названия страницы.[1] Кроме того, каждое изменение в формулировке приводит к обновлению индекс поиска течение нескольких секунд.

Существует много индексов «полного текста» вики-сайта для разных видов поиска. Полный вики-текст индексируется много раз во много специальных индексов, каждый из которых парсит вики-текст так, чтобы оптимизировать его использование. Примеры:

  • «Вспомогательный» текст, включающий примечания, подписи, содержание, а также вики-текст, классифицированный HTML-атрибутом class=searchaux.
  • «Вступительный» текст — вики-текст, идущий до первого заголовка.
  • Текст с названиями «категорий» — список категорий внизу страницы.
  • Шаблоны индексируются. Если текст шаблона изменится, то все страницы со включением шаблона изменятся. (Это может занять большое время в зависимости от очереди задач). Если изменится шаблон, используемый в другом шаблоне, то этот индекс обновится.
  • Содержимое документов в пространствах имён Файл/Media теперь также индексируется. Распознаются тысячи форматов.

Реализована поддержка для десятков языков, но желательна поддержка всех языков. Список поддерживаемых языков: elasticsearch.org; чтобы отправить запрос или правку, смотрите документацию о вкладе в проект. Third-party open-source libraries are also used to support additional languages not covered by Elasticsearch.

CirrusSearch will optimize your query, and run it. The resulting titles are weighted by relevance, and heavily post-processed, 20 at a time, for the search results page. For example snippets are garnered from the article, and search terms are highlighted in bold text.

Search results will often be accompanied by various preliminary reports. These include Did you mean (spelling correction), and, when no results would otherwise be found it will say Showing results for (query correction) and search instead for (your query).

К функциям поиска также относятся:

  • Сортировка результатов по количеству входящих ссылок.
  • Символ тильды ~ в начале поисковой строки для отключения навигации и подсказок с сохранением рэнкинга страниц.
  • Интеллектуальное сопоставление символов путем нормализации (или «свёртывания»), т.е. приведения символов, которые не вводятся с клавиатуры, в символы, вводимые с клавиатуры.
  • На странице результатов поиска найденные слова и фразы выделяются полужирным начертанием. Механизм выделения работает уже после индексного поиска, который находит страницу, поэтому выделение может не всегда быть корректным, особенно для регулярных выражений (regex). Маркер выделения может быть более или менее точным, чем индексатор.

Слова, фразы и поисковые модификаторы

Просто поисковой запрос представляет собой слово или "фразу в кавычках". Details vary by language, especially for languages without spaces, but search typically recognizes a "word" to be:

  • строка цифр
  • строка букв
  • подслова ограниченные переходами буква/цифра, как в txt2regex
  • подслова внутри составногоИмени с использованием camelCase

«Стоп-слова» — это слова, игнорируемые поиском (например, из-за их широкой распространённости или по иным причинам). The list of stop words is language-specific and not all languages support stop words.[2] A given search term matches against content (rendered on the page). To match against wikitext instead, use the insource search parameter (See section below). Each search parameter has its own index, and interprets its given term in its own way.[3]

Spacing between words, phrases, parameters, and input to parameters, can include generous instances of whitespace and greyspace characters. "Greyspace characters" are all the non-alphanumeric characters ~!@#$%^&()_+-={}|[]\:";'<>?,./. A mixed string of greyspace characters and whitespace characters, is "greyspace", and is treated as one big word boundary. Greyspace is how indexes are made and queries are interpreted.[4]

Two exceptions are where 1) an embedded:colon is one word (it being treated as a letter), and 2) an embedded comma , such as in 1,2,3, is treated as a number. Greyspace characters are otherwise ignored unless, due to query syntax, they can be interpreted as modifier characters.

The modifiers are ~ * \? - " ! . Depending on their placement in the syntax they can apply to a term, a parameter, or to an entire query. Word and phrase modifiers are the wildcard, proximity, and fuzzy searches. Each parameter can have their own modifiers, but in general:

  • A fuzzy-word or fuzzy-phrase search can suffix a tilde ~ character (and a number telling the degree).
  • A tilde ~ character prefixed to the first term of a query guarantees search results instead of any possible navigation.
  • A wildcard character inside a word can be an (escaped) question mark \? for one character or an asterisk * character for zero or more characters.
  • Truth-logic can interpret AND and OR, but parameters cannot. Note that the AND and OR operators currently do not function in the traditional truth-logic manner! For details see more on logical operators.
  • Truth-logic understands - or ! prefixed to a term to invert the usual meaning of the term from "match" to "exclude".
Words that begin with - or !, such as -in-law or !Kung can exactly match titles and redirects, but will also match every document that does not contain the negated word, which is usually almost all documents. To search for such terms other than as exact matches for titles or redirects, use the insource search parameter (See section below).
  • Quotes around words mark an "exact phrase" search. For parameters they are also needed to delimit multi-word input.
  • Stemming is automatic but can be turned off using an "exact phrase".
The two wildcard characters are the star and the (escaped) question mark, and both can come in the middle or end of a word. The escaped question mark \? stands for one character and the star * stands for any number of characters. Because many users, instead of writing a query, will ask a question, any question mark is ignored unless purposefully escaped \? into its wildcard meaning.

A phrase search can be initiated by various hints to the search engine. Each method of hinting has a side-effect of how tolerant the matching of the word sequence will be. For greyspace, camelCase, or txt2number hints:

  • given words-joined_by_greyspace(characters) or wordsJoinedByCamelCaseCharacters it finds words joined by ... characters, in their bare forms or greyspace forms.
  • txt2number will match txt 2 number or txt-2.number.
  • Stop words are enabled for the edge cases (in the periphery) of a grey_space or camelCase phrase. An example using the, of, and a is that the_invisible_hand_of_a matches invisible hand within the text meetings invisible hand shake.

A "search instead" report is triggered when a universally unknown word is ignored in a phrase.

Each one of the following types of phrase-matching contains and widens the match-tolerances of the previous one:

  • An "exact phrase" "in quotes" will tolerate (match with) greyspace. Given "exact_phrase" or "exact phrase" it matches "exact]phrase".
  • A greyspace_phrase initiates stemming and stop word checks.
  • Given CamelCase it will additionally match camelcase, in all lowercase, because CirrusSearch is not case sensitive in matching.

Note that CamelCase matching is not enabled for all languages.

Some parameters interpret greyspace phrases, but other parameters, like insource only interpret the usual "phrase in quotes".

In search terminology, support for "stemming" means that a search for "swim" will also include "swimming" and "swimmed", but may not include irregular forms like "swam".
Поисковая фраза parserfunction parserFunction parser function parser-function parser:function parSer:funcTion
parserfunction Yes Yes N N N N
"parser function" N N Yes Yes N N
parser_function N Yes Yes Yes N N
parserFunction Yes Yes Yes Yes N N
"parser:function" N N N N Yes Yes
"parser_function" N N Yes Yes N N
"parSer_funcTion" N N Yes Yes N N
parSer_FuncTion N N Yes Yes Yes Yes

Note that all stemming is case insensitive.

Note how the "exact phrase" search interpreted the embedded:colon character as a letter, but not the embedded_underscore character. A similar event occurs with the comma , character inside a number.

Given in:this:word, CirrusSearch, when in an "exact phrase" context, (which includes the insource parameter context), will not match in, this, or word, but will then only match in:this:word.

Otherwise, remember that for CirrusSearch words are letters, numbers, or a combination of the two, and case does not matter.

The common word search employs the space character and is aggressive with stemming, and when the same words are joined by greyspace characters or camelCase they are aggressive with phrases and subwords.

When common words like "of" or "the" are included in a greyspace-phrase, they are ignored, so as to match more aggressively.

A greyspace_phrase search term, or a camelCase, or a txt2number term, match the signified words interchangeably. You can use any of those three forms.[5] Now camelcase matches camelCase because Search is not case sensitive, but camelCase matches camelcase because camelCase is more aggressive. Like the rest of Search, subword "words" are not case-sensitive. By comparison the "exact phrase" is greyspace oriented and ignores numeric or letter-case transitions, and stemming. "Quoted phrases" are not case sensitive.

From the table we can surmise that the basic search parser_function -"parser function" is the sum of the basic searches parserFunction and parser<stems> function<stems>.

Making inquiries with numbers, we would find that:

  • Plan9 or Plan_9 matches any of: plan9, plans 9, planned 9th, (planned) 9.2, "plans" (9:24)
  • "plan9" only matches plan9 (case insensitive)
  • Plan*9 matches plan9 or planet4589.

The star * wildcard matches a string of letters and digits within a rendered word, but never the beginning character. One or more characters must precede the * character.

  • When * matches numbers, a comma is considered part of one number, but the decimal point is considered a greyspace character, and will delimit two numbers.
  • Inside an "exact phrase" * is treated as a greyspace character and not a wild card character, so it delimits words.

The \? wildcard represents one letter or number; *\? is also accepted, but \?* is not recognized.

The wildcards are for basic word, phrase, and insource searches, and may also be an alternative to (some) advanced regex searches (covered later).

Putting a tilde ~ character after a word or phrase activates a fuzzy search.

  • For a phrase it is termed a proximity search, because proximal words are tolerated to an approximate rather than exact phrase.
  • For example, "exact one two phrase"~2 matches exact phrase.
  • For a word it means extra characters or changed characters.
  • For a phrase a fuzzy search requires a whole number telling it how many extra words to fit in, but for a word a fuzzy search can have a decimal fraction, defaulting to word~0.5 (word~.5), where at most two letters can be found swapped, changed, or added, but never the first two letters.
  • For a proximity phrase, a large number can be used, but that is an "expensive" (slow) search.
  • For a word word~2 is most fuzzy with an edit distance of 2 (default), and word~1 is least fuzzy, and word~0 is not fuzzy at all.
flowers algernon Flowers for Algernon flowers are for Algernon Flowers a1 2b 3c 4f 5j 6l 7j 8p q9 z10 for Algernon
"flowers algernon" Yes N N N
"flowers algernon"~0 Yes N N N
"flowers algernon"~1 Yes Yes N N
"flowers algernon"~2 Yes Yes Yes N
"flowers algernon"~11 Yes Yes Yes Yes
"algernon flowers"~1 N N N N
"algernon flowers"~2 Yes N N N
"algernon flowers"~3 Yes Yes N N
"algernon flowers"~4 Yes Yes Yes N
"algernon flowers"~13 Yes Yes Yes Yes

For the closeness value necessary to match in reverse (right to left) order, count and discard all the extra words, then add twice the total count of remaining words minus one. (In other words, add twice the number of segments). For the full proximity algorithm, see Elasticsearch slop.

Кавычки предполагают точное соответствие запросу (то есть отключают дополнение по словоформам - т.н. «стемминг»); добавление тильды ("but appending"~) включает стемминг снова.

flowers flower Flowers for Algernon flower for Algernon
flowers Yes Yes Yes Yes Stemming is in effect.
"flowers" Yes N Yes N Proximity search turns off stemming.
"flowers"~ Yes Yes Yes Yes Proximity plus stemming by suffixing a tilde.
"flowers for algernon" N N Yes N Proximity search turns off stemming.
"flowers for algernon"~ N N Yes Yes Proximity plus stemming by suffixing a tilde.
"flowers algernon"~1 N N Yes N Proximity search turns off stemming.
"flowers algernon"~1~ N N Yes Yes Proximity plus stemming by suffixing a tilde.

Insource

1.24
Gerrit change 137733

Insource searches can be used to find any one word rendered on a page, but it's made for finding any phrase you might find - including MediaWiki markup (aka wikicode), on any page except redirects. This phrase completely ignores greyspace: insource: "state state autocollapse" matches |state={{{state|autocollapse}}}.

insource: word
insource: "word1 word2"
Greyspace characters are ignored, just as they are with word searches and exact-phrase searches.
insource:/regexp/
insource:/regexp/i
These are regular expressions. They aren't efficient, so only a few are allowed at a time on the search cluster, but they are very powerful. The regular expression matches case-sensitively by default; case-insensitivity can be opted in with the extra i, which is even less efficient.

Insource complements itself. On the one hand it has full text search for any word in the wikitext, instantly. On the other hand it can process a regexp search for any string of characters.[6] Regexes scan all the textual characters in a given list of pages; they don't have a word index to speed things up, and the process is interrupted if it runs for more than twenty seconds. Regexes run last in a query, so to limit needless character-level scanning, every regex query should include other search terms to limit the number of documents that need to be scanned.[7] Often the best candidate to add to the regex query insource:/arg/ is insource:arg, where arg is the same (and uses no wildcards).

The syntax for the regexp is insource: no space, and then /regexp/. (No other parameter disallows a space. All the parameters except insource:/regexp/ accept space after their colon.)

Insource indexed-search and regexp-search roles are similar in many respects:

  • Both search wikitext only.
  • Neither finds things "sourced" by a transclusion.
  • Neither does stemmed, fuzzy, or proximity searches.
  • Both want the fewest results, and both work faster when accompanied by another clause.

But indexed searches all ignore greyspace; wildcards searches do not match greyspace, so regexes are the only way to find an exact string of any and all characters, for example a sequence of two spaces. Regexes are an entirely different class of search tool that make matching a literal string easy (basic, beginner use), and make matching by metacharacter expressions possible (advanced use) on the wiki. See #Regular expression searches below.

The insource parameter treats words with embedded colons as one word. This affects search queries for templates, parser functions, URLs, wikilinks, HTML tags, and comments.
When possible, please avoid running a bare regexp search. See how this is always possible at #Regular expression searches, below.
To search for words that begin with - or !, such as -in-law or !Kung, use a case-insensitive insource query together with a simple search on the "plain" version of the term (to avoid a bare regexp search). For example, "in-law" insource:/-in-law/i or "kung" insource:/!kung/i.

Префикс и пространство имён

Prepending a namespace term like file: to a search query limits results to a specific namespace , instead of searching the entire wiki. The default namespace is "Main".

Only one namespace name can be set from the search box query. It must be the first term in the query, or, if used as part of a prefix: term, must appear as the last term in the query.

Two or more namespaces may be searched from the Advanced pane of the search bar found on the top of every search results page, Special:Search. Your search domain, as a profile of namespaces, can be set here. The namespaces list will then present itself on the first page of future search results to indicate the search domain of the search results. To unset this, select the default namespace (shown in parentheses), select "Remember", and press Search.

The search bar graphically sets and indicates a search domain. "Content pages" (mainspace), "Multimedia" (File), "Everything" (all plus File), "Translations", etc., are hyperlinks that can activate the query in that domain, and then indicate this by going inactive (dark). But the query will override the search bar. When a namespace or prefix is used in the query the search bar activations and indications may be misleading, so the search bar and the search box are mutually exclusive (not complementary) ways to set the search domain.

A namespace term overrides the search bar, and a prefix: term overrides a namespace.

To specify a namespace name, prefix it with a colon, e.g., talk:. Use all: to search across all namespaces, or : (a single colon) to search just the main article namespace.

The all: term does not include the File: namespace, which includes media content held at Commons such as PDF, which are all indexed and searchable. When File is involved, a namespace modifier local: has an effect, otherwise it is ignored.

As with search parameters, local: and all: must be lowercase. Namespaces names, though, are case insensitive.

Namespace aliases are accepted.

talk: "Wind clock" Find pages in the Talk namespace whose title or text contains the phrase "wind clock".
file: "Wind clock" Find pages in File namespace, whose title, text, or media content contains the phrase "wind clock".
file: local: "Wind clock" Filter out results from Commons wiki.
local: "Wind clock" Ignored. Searches mainspace. Local is ignored unless File is involved.

prefix:

The prefix: parameter matches any number of first-characters of all pagenames in one namespace.[8] When the first letters match a namespace name and colon, the search domain changes.

Given a namespace only, prefix: will match all its pagenames. Given one character only, it cannot be - (dash), ' (quote), or " (double quote). The last character cannot be a colon.

For pagenames that match, their subpage titles match by definition.

The prefix: parameter does not allow a space before a namespace, but allows whitespace before a pagename. This term always goes at the end, so that pagename characters may contain quotation marks (").

prefix:cow Find pages in mainspace whose title starts with the three letters c o w.
domestic   prefix:cow Find pages in mainspace whose title starts with the three letters c o w, and that contain the word "domestic".
domestic   prefix:cow/ List any existing subpages of Cow but only if they contain the word "domestic". This is a very common search and is frequently built using a special URL parameter called prefix=.
domestic   prefix:Talk:cow/ List any subpages of Talk:cow, but only if they contain the word "domestic".
1967   prefix:Pink Floyd/ List any subpages of Pink Floyd, but only if it also contains the word "1967".

The Translate extension creates a sort of "language namespace" of translated versions of a page. However, unlike namespace or prefix, which create the initial search domain, the inlanguage parameter is a filter of it. (See the next section.)

Исключение материалов из поискового индекса

Content can be excluded from the search index by adding class="navigation-not-searchable". This will instruct CirrusSearch to ignore this content from the search index (see задача T162905 for more context).

Additionally content can be marked as auxiliary information by adding class="searchaux". This will instruct CirrusSearch to move the content from the main text to an auxiliary field which has lower importance for search and snippet highlighting. This distinction is used for items such as image thumbnail descriptions, 'see also' sections, etc.

Фильтры

A filter will have multiple instances, or negated instances, or it can run as a standalone filtering a search domain. A query is formed as terms that filter a search domain.

Adding another word, phrase, or parameter filters more. A highly refined search result may have very many Y/N filters when every page in the results will be addressed. (In this case ranking is largely irrelevant.) Filtering applies critically to adding a regex term; you want as few pages as possible before adding a regex (because it can never have a prepared index for its search).

A namespace is a specified search domain but not a filter because a namespace will not run standalone. A prefix will negate so it is a filter. The search parameters below are filters for which there may be multiple instances.

Insource (covered above) is also a filter, but insource:/regexp/ is not a filter. Filters and all other search parameters are lowercase. (Namespaces are an exception, being case insensitive.)

«Intitle» и «incategory»

Word and phrase searches match in a title and match in the category box on bottom of the page. But with these parameters you can select titles only or category only.

  • cow*
    • Find articles whose title or text contains words that start with cow
  • intitle:foo
    • Find articles whose title contains foo. Stemming is enabled for foo.
  • intitle:"fine line"
    • Find articles whose title contains fine line. Stemming is disabled.
  • intitle:foo bar
    • Find articles whose title contains foo and whose title or text contains bar.
  • -intitle:foo bar
    • Находит статьи с заголовком, который не содержит "foo" и "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:"musicals" incategory:"1920"
    • Find articles that are not in Category:Musicals but are in Category:1920

Intitle and incategory are old search parameters. Incategory no longer searches any subcategory automatically, but you can now add multiple category pagenames manually.

1.31
Gerrit change 413896

Since MediaWiki 1.31-wmf.23 Regular expression searches are supported for intitle:

intitle:/regex/, intitle:/regex/i

Everything written in the #Regular expression searches is also valid for these searches, including warnings.

When possible, please avoid running a bare regexp search. See how this is always possible at #Regular expression searches, below.

Deepcategory

Deep category search allows to search in category and all subcategories. The depth of the tree is limited by 5 levels currently (configurable) and the number of categories is limited by 256 (configurable). The deep search uses SPARQL Category service from WDQS. Keywords are deepcategory or deepcat. Example:

  • deepcat:"musicals"
    • Find articles that are in Category:Musicals or any of the subcategories.

The DeepCat gadget that previously implemented the parameter was sunsetted in January 2020.

Ссылки на …

Linksto finds wikilinks to a given name, not links to content. The input is the canonical, case sensitive, page name. It must match the title line of the content page, exactly, before any title modifications of the letter-case. (It must match its {{FULLPAGENAME}}, e.g. Help:CirrusSearch/ru.)

Linksto does not find redirects. It only finds [[wikilinks]], even when they are made by a template. It does not find a link made by a URL, even if that URL is an internal wiki link.

To find all wikilinks to a "Help:Cirrus Search", if "Help:Searching" and "H:S" are redirects to it:

  1. linksto: "Help:Cirrus Search"
  2. linksto: Help:Searching
  3. linksto: H:S

CirrusSearch -linksto: Help:CirrusSearch finds articles that mention "CirrusSearch" but not in a wikilink.

Ускорение

You can specify template usage with hastemplate: template. Input the canonical pagename to find all usage of the template, but use any of its redirect pagenames finds just that naming. Namespace aliases are accepted, capitalization is entirely ignored, and redirects are found, all in one name-search. (Compare boost-template no default namespace; linksto no namespace aliases, case-sensitive, no redirects; intitle no redirects.)

Hastemplate finds secondary (or meta-template) usage on a page: it searches the post-expansion inclusion. This is the same philosophy as for words and phrases from a template, but here it's for templates from a template. The page will be listed as having that content even though that content is not seen in the wikitext.

  • hastemplate: "quality image", finds "Template:Quality image" usage in your default search domain (namespaces).
  • hastemplate: portal:contents/tocnavbar, finds mainspace usage of a "Contents/TOCnavbar" template in the Portal namespace.

For installations with the Translate extension, hastemplate searches get interference wherever Template:Translatable template name wraps the template name of a translatable template. Use insource instead.

Язык

For installations with the Translate extension, inlanguage is important for highly refined searches and page counts.

inlanguage: код языка

will produce search results in that language only.

Например

  • to count all Japanese pages on the wiki
all: inlanguage: ja
  • to filter out German and Spanish pages in the Help namespace
help: -inlanguage: de -inlanguage: es
  • to ignore Translate, and where English is the base language, add
inlanguage:en

Contentmodel

The contentmodel: keyword allows to limit the search to pages of a specific content model. For possible models cf. Content handlers. E.g.:

  • To see only JSON pages:
contentmodel:json

subpageof

To find sub-pages.

subpageof: ParentPage

Например

  • To find all subpages of CirrusSearch.
subpageof:CirrusSearch
  • Use double quotes if the parent page contains spaces.
subpageof:"Requests for comment"
unlike prefix:, do not include the page namespace in the keyword value. If you want to limit to sub-pages of a particular namespace use the namespace filter.

Articletopic

The articletopic: keyword allows filtering search results by topic. For possible topics see Help:CirrusSearch/articletopic . E.g. articletopic:books will filter the search results to articles about books. articletopic:books|films will filter to articles about books or films. articletopic:books articletopic:films will filter to articles which are about both books and films.

Only mainspace articles belong into topics, and topics are only available on Wikipedias. Unlike other filters, articletopic also does page weighting: articles which are a stronger match for a topic will be higher in the search results (while articles which aren't about that subject at all will be removed from the result set completely).

Topic models are derived via machine learning from ORES. Any given article receives a score on dozens of different topics, and therefore may appear under different keywords. For instance, the article on Albert Einstein may appear as a "physics" article and a "biography" article. All Wikipedias have scores available -- some have local-language topic models that have coverage on all articles. Other languages do not have local ORES models, and are using English-language scores assigned to articles in the local language that also exist in English Wikipedia. The languages with such "cross-wiki" scores do not have 100% coverage -- depending on the language, it may only be something like 60% of articles that have topics available.

Topic-related search data is updated weekly, so recently created articles might not show up in topic-based search queries.

Pageid

The pageid: keyword restricts search results to the given set of page IDs. This is not really useful for manual searching; it can be used by software tools for checking whether a set of pages match the given set of search conditions (e.g. for re-validating cached search results).

Вес страниц

Weighting determines snippet, suggestions, and page relevance. The normal weight is one. Additional weighting is given through multipliers.

If the query is just words, pages that match them in order are given a boost. If you add any explicit phrases to your search, or for certain other additions, this "prefer phrase" feature is not applied.

Morelike

  • morelike:page name 1|page name 2|...|page name n
    • Ищет статьи, текст которых содержит слова, похожие на текст заданных статей.
  • morelike:wasp|bee|ant
    • Find articles about stinging insects.
  • morelike:template:search|template:regex|template:usage
    • Find templates about regex searching for template usage on the wiki.

morelike is a "greedy" keyword, meaning that it cannot be combined with other search queries. If you want to use other search queries, use morelikethis in your search:

  • morelikethis:bee hastemplate:"featured article"
    • Find articles about bees that also have the "featured article" template.

The morelike: 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:

  • cirrusMltMinDocFreq: Minimum number of documents (per shard) that need a term for it to be considered.
  • cirrusMltMaxDocFreq: Maximum number of documents (per shard) that have a term for it to be considered.
  • cirrusMltMaxQueryTerms: Maximum number of terms to be considered.
  • cirrusMltMinTermFreq: Minimum number of times the term appears in the input to doc to be considered. For small fields (title) this value should be 1.
  • cirrusMltMinWordLength: Minimal length of a term to be considered. Defaults to 0.
  • cirrusMltMaxWordLength: The maximum word length above which words will be ignored. Defaults to unbounded (0).
  • cirrusMltFields (comma separated list of values): These are the fields to use. Allowed fields are title, text, auxiliary_text, opening_text, headings and all.
  • cirrusMltUseFields (true|false): use only the field data. Defaults to false: the system will extract the content of the text field to build the query.
  • cirrusMltPercentTermsToMatch: The percentage of terms to match on. Defaults to 0.3 (30 percent).
  • Example:
    &cirrusMtlUseFields=yes&cirrusMltFields=title&cirrusMltMinTermFreq=1&cirrusMltMinDocFreq=1&cirrusMltMinWordLength=2
    

These settings can be made persistent by overriding cirrussearch-morelikethis-settings in System message.

Prefer-recent

Adding prefer-recent: anywhere in the query gives recently edited articles a slightly larger than normal boost in the page-ranking rules. Prefer-recent is only applied when using the default relevance sort order.

It defaults to boost only 60% of the score, in a large, 160-day window of time, which can be entered in the query as prefer-recent:0.6,160. This plays well with other page ranking rules, and is intended for most searches.

You can manipulate the rules: prefer-recent:boost,recent Technically, "boost" is the proportion of score to scale, and "recent" is the half life in days. The boost is more than the usual multiplier, it is an exponential boost. The factor used in the exponent is the time since the last edit.

Например

prefer-recent:,7

Pages older than 7 days are boosted half as much, and pages older than 14 days are boosted half as much again, and so on. For a simple "sort by date" in highly refined search results, where page ranking and boosting are largely meaningless, just boost the entire score.

  • prefer-recent:1,7 - weeks
  • prefer-recent:1,1 - days
  • prefer-recent:1,0.0007 - minutes
  • prefer-recent:1,0.0001 - 8.64 seconds
  • prefer-recent:1,0.00001 - seconds

Boost-templates

Можно увеличить поисковую оценку страниц в зависимости от того, какие шаблоны они содержат. Это можно сделать прямо в поисковом запросе при помощи boost-templates:"" или установив умолчание для всех запросов через сообщение MediaWiki:Cirrussearch-boost-templates. boost-templates заменяет содержимое cirrussearch-boost-templates, если оно было указано. Синтаксис слегка специфический, но выбран для наглядности.

Вы можете повысить поисковый рейтинг страниц в зависимости от того, какие шаблоны они содержат. Это можно применить ко всем поисковым запросам, объявив повышение с помощью MediaWiki:Cirrussearch-boost-templates, или вручную, в отдельных запросах с помощью оператора boost-templates:"". Если в запросе задан оператор boost-templates, то содержимое cirrussearch-boost-templates игнорируется. Similar to the prefer-recent feature, boost-templates is applied as part of the default relevance sort order. It has no effect on other search orders.

The syntax of the message is as follows:

  • Everything from a # character to the end of the line is considered a comment, and ignored.
  • Every non-blank line is interpreted as the exact name of a template that should receive boosting (including namespace prefix), followed by a pipe "|" character, followed by a number, followed by a "%" character.

Good examples:

 Template:Important|150%
 Template:Very_Very_Important|300%
 Template:Less_important|50%

Bad examples:

 Template:Foo|150.234234% # decimal points are not allowed.
 Foo|150% # technically valid, but acts on transclusions of Foo (main space article) instead of Template:Foo.

Некоторые примеры:

boost-templates:"Template:Quality_Image|200%" incategory:china
Ищет файлы в категории "Китай", сортируя качественные изображения в начало.
boost-templates:"Template:Quality_Image|200% Template:Low_Quality|50%" incategory:china
Ищет файлы в категории "Китай", сортируя высококачественные изображения в начало, а низкокачественные - в конец.
boost-templates:"Template:Quality_Image|200% Template:Low_Quality|50%" popcorn
Find files about popcorn, sorting quality images first and low-quality images last. Remember that through the use of the cirrussearch-boost-templates message this can be reduced to just popcorn.

Десятичные точки в процентных значениях не допускаются. Поисковый рейтинг страниц формируется таким образом, что доли процента вряд ли будут иметь значение.

Beware that if you add very low or very high percentages via cirrussearch-boost-templates, they can poison the full-text scoring. For example, if Wikipedia were to boost the "Featured article" template by 1 million percent, then, searches for any term mentioned in featured articles, would rank the featured article above even the dedicated article about that term.

Phrase matching would be similarly blown away, so a search like brave new world would return a featured article as first result even if it merely has those three words mentioned throughout it, instead of the more relevant article about Brave New World itself.

Регулярные выражения для поиска

Внимание Внимание: Do not run a bare insource:/regexp/ search. It will probably timeout after 20 seconds anyway, while blocking the queries of responsible users.

Базовый поиск по индексу находит "слово", отображаемое на странице. Дефисы, знаки препинания, кавычки, слэши и другие математические и вычислительные символы - лишь границы "слов". Их нельзя использовать при поиске по индексу. Mostly that search behavior is wanted by the user. However, sometimes one wants to have the ability for a more precise search.

To get around the syntactic deficiency of index-based searches regexp searches can be used. But as queries with only regexp expressions are very slow and resource consuming, they should always be combined with an index-based search, such that the regexp search-domain gets limited to the results of one or more index-based search.

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 develops a simple filter to generate the search domain for the regex engine to search (index based search domain marked bold, regexp part marked in italics):

  • insource:"debian.reproducible.net" insource:/debian\.reproducible\.net/
  • insource:"c:\program files (x86)" insource:/C\:\\Program Files \(x86\)/i
  • insource:"<tag>{{template}}</tag>" insource:/"<tag>{{template}}<"\/"tag>"/
  • insource:"[[title|link label]]'s" insource:/"[[title|link label]]'s"/
  • insource:/regexp/ prefix:{{FULLPAGENAME}}

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:{{FULLPAGENAME}}]] finds the term regex on this page.

A query with no namespace specified and no prefix specified searches your default search domain, (settable on any search-results page, i.e. at Special:Search). Some users keep their default search domain at "all namespaces", i.e. the entire wiki. On a large wiki if this user does a bare regexp search it will probably fail, incurring a 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 an insource:// (a regexp of any kind), consider adding 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 (without regex search), 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.

To test a bare regexp query you can create a page with test patterns, and then use the prefix parameter with that fullpagename. The match will be highlighted. It searches that page (in the database) and its subpages.

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

Мета-символы

This section covers how to escape metacharacters used in regexp searches. For the actual meaning of the metacharacters see the explanation of the syntax.[9]

The use of an exact string requires a regexp, but the regexp term obligates the search to limit itself. Add a regexp term, never search a bare regexp. Start by noting the number of pages in a previous search before committing an exact string search. Querying with an exact string requires a filtered search domain.

Например:

  • to search a namespace, gauge the number of pages with a single term that is a namespace. This will list the number of pages in that namespace.
  • starting out to find again what you may have seen, like "wiki-link" or "(trans[in]clusion)" start with namespace and insource filters.

There are some notable differences from standard regex metacharacters:

  • The \n or \r\n are not reserved for matching a newline.

To search for a string that contains a newline, you can do a search like insource:/[^\}]\}\}[^\} \|]{2}\<noinclude/i which means not a curly brace, then two curly braces, then any two characters except a curly brace, space, or pipe, then a ‎<noinclude> tag. The "any character except" will include a newline in the search. Note thas this search was designed only to match to the following string:

}}

<noinclude>
  • The dot . metacharacter stands for any character including a newline, so .* matches across lines.
  • The number # sign means something, and must be escaped.

[10]

  • The ^ and $ are not implemented. 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.
  • < and > 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.

Substitutions for some metacharacters

While character classes \n, \s, \S are not supported, in case of an acute need to use them in a regular expression, you may use these workarounds:

PCRE CirrusSearch Description
\n [^ -􏿿] A newline (also can find a tabulation character)
[^\n] [ -􏿿] Any character except for a newline (and tabulation; you can add it to character set to include it as well)
\s [^!-􏿿] A white space character: space, newline, or tabulation
\S [!-􏿿] Any character except for white space characters (not a space, not a newline, and not a tabulation)

In these ranges, " " (space) is used as the character immediately following control characters, "!" – the character immediately following it, and "􏿿" as the U+10FFFF character, which is the last character in Unicode. Thus, the range from " " to "􏿿" includes all characters except for control ones, of which articles may contain newlines and tabs, while the range from "!" to "􏿿" includes all characters except for control ones and the space.

Refining with an exact string

  • refining an ongoing search process with what you want to see, like "2 + 2 = 4", or "site.org" This is ideally the best use of regex, because it adds it as a single regexp term while refining a search, the limited number of pages the regexp must crawl is can be seen.

You can start out intending an exact string search, but keep in mind:

  • 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. 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. Escaping with quotes is cleaner.
  • 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.

  • /"[[page/name|{{temp-late"/ instead of /\[\[page\/name\|\{\{temp\-late/
  • /"literal back\slash"/ is as good as /literal back\\slash/
  • But /"This \" fails"/ always.
  • And /"This \/ depends"/. 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 escaped metacharacters would be \~\@\#\&\*\(\)\-\+\{\}\[\]\|\<\>\?\.\\.
  • The equivalent expression escaped with double-quotes 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 the/str"ing out. (The /" delimiters "/ are not shown.)
  1. Replace " with "\"" (previous double-quote: stop, concatenate, quote restart).
  1. Replace / with "\/" (stop, concatenate, start).
  1. You get insource:/"the"\/"str"\""ing"/, showing concatenation of the two methods.
While refining a regexp on a search results page, keep in mind that the snippet "wikitext" has modified spacing. Regex are sensitive to space characters, so copying from snippets is dangerous.

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 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 a character that is either a dash or a right square bracket or a dot: [-.\]] or [].\-].

For general examples using metacharacters:

  • insource:"2+2=4" insource:/"2+2=4"/ matches "2 + 2 = 4", with zero spaces between the characters.
  • insource:"2 + 2 = 4" insource:/2 ?\+ ?2 ?= ?4\./ match with zero or one space in between. The equals = sign is not a metacharacter, but the plus + sign is.
  • insource:"<tag>[[link|2\3?]]\</tag>" insource:/"<tag>[[link|2\3?]]<"\/"tag>"/

Регулярные выражения для заголовков

The insource keyword does only search the page source content. To run regex searches on the title strings intitle:/regex/ can be used.

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):

hastemplate:val insource:"fmt commas" insource:/\{\{ *[Vv]al *\|[^}]*fmt *= *commas/ insource:/\{\{ *[Vv]al *\|[^}]*[-+]?[0-9]{3,4} *[|}]/

Note that the = sign in "fmt commas" is not needed but that adding it would not change the search results. It is fast because it uses two filters so that every page the regexp crawls has the highest possible potential.

Гео-поиск

Searching based on the (primary) coordinates associated with pages. Зависит от Расширение:GeoData и {{#coordinates:}}

bounded

You can limit search to pages identified as being near some specified geographic coordinates. The coordinates can either be specified as a <lat>,<lon> pair, or by providing a page title from which to source the coordinates. A distance to limit the search to can be prepended if desired. Примеры:

  • neartitle:"San Francisco"
  • neartitle:"100km,San Francisco"
  • nearcoord:37.77666667,-122.39
  • nearcoord:42km,37.77666667,-122.39

boosted

You can alternatively increase the score of pages within a specified geographic area. The syntax is the same as bounded search, but with boost- prepended to the keyword. This effectively doubles the score for pages within the search range, giving a better chance for nearby search results to be near the top.

  • boost-neartitle:"San Francisco"
  • boost-neartitle:"100km,San Francisco"
  • boost-nearcoord:37.77666667,-122.39
  • boost-nearcoord:42km,37.77666667,-122.39

Поиск свойств файлов

1.28
Gerrit change 311061

Since MediaWiki 1.28, CirrusSearch supports indexing and searching of properties of files in the File: namespace. This includes:

  • file media type
  • MIME type
  • size
  • width & height
  • resolution
  • bit depth for files that support these
While these predicates are useful only for files, they by themselves do not limit search to the File: namespace. It is recommended to include this namespace in a search or restrict the search to only this namespace when using these conditionals.

Тип файла (filetype)

Searching for file type allows to retrieve files according to their classification, such as office documents, videos, raster images, vector images, etc. The following types currently exist:

  • UNKNOWN
  • BITMAP
  • DRAWING
  • AUDIO
  • VIDEO
  • MULTIMEDIA
  • OFFICE
  • TEXT
  • EXECUTABLE
  • ARCHIVE

This list may be extended in the future. See also MEDIATYPE_* constants in Defines.php.

The syntax of the search is: filetype:{type}. Example:

filetype:video - ищет во всех видео

The filetype search is not case-sensitive.

filemime

Matches file MIME type. The syntax is:

filemime:{MIMEtype} - look for files of this MIME type

The argument can be quoted to specify exact match. Without quotes, partial matches to components of MIME type will be accepted too.

Примеры:

  • filemime:"image/png" - look for files with MIME type exactly image/png
  • filemime:pdf - look for all PDF documents
  • -filemime:pdf - skip all PDF documents (notably on Commons)

The MIME type search is not case-sensitive.

filesize

Search for file of given size, in kilobytes (kilobyte means 1024 bytes). The syntax is:

  • filesize:{number} или filesize:>{number} - file with size at least given number
  • filesize:<{number} - file with size no more than given number
  • filesize:{number},{number} - file with size between given numbers

Примеры:

  • filesize:>20 или filesize:20 - files 20KB and bigger
  • filesize:<1024 - файлы меньше, чем 1МБ
  • filesize:100,500 - files with sizes between 100KB and 500KB

Параметры файлов

It is possible to search for specific file measures: width, height, resolution (which is defined as square root of height × width), and bit depth. Not all files may have these properties. The syntax is:

  • {measure}:{number} - file with measure that equals to given number
  • {measure}:>{number} - file with measure that is at least given number
  • {measure}:<{number} - file with measure that is no more than given number
  • {measure}:{number},{number} - file with measure that is between given numbers

Where measure can be:

filew или filewidth - ширина файла

fileh or fileheight - file height

fileres - file resolution (see above)

filebits - file bit depth

Примеры:

filew:>800 fileh:>600 - files that are at least 800×600 pixels in size

filebits:16 - files with 16-bit color depth

fileheight:100,500 - file between 100 and 500 pixels high

Wikibase search

The Wikibase extension defines some search keywords in order to make it easier to search for certain Wikibase items. This is useful on Wikidata and other Wikibase sites, including to search for images with Structured data on Wikimedia Commons . See Help:WikibaseCirrusSearch for details.

Результаты поиска в других вики-проектах («кросс-вики»)

There are two kinds of cross-wiki results that may be shown when searching on Wikipedia.

Cross-project search (also known as interwiki search, sister search, or sister projects search) shows additional results from other projects (Wiktionary, Wikisource, Wikiquote, etc.) shown to the side on the Wikipedia results page. Cross-project search is available on most Wikipedias with sister projects.

Cross-language search (see blog post) refers to additional results shown below the main results that are from a Wikipedia in a different language. Cross-language search uses a heavily modified and optimized version of a light-weight language detector called TextCat . Cross-language search is currently only available on a few Wikipedias (see TextCat link for details).

Explicit sort orders

In addition to the default relevance based sort, CirrusSearch can provide results using a few other explicit sort orders. Specifying a sorting order other than relevance will disable all search keywords that affect scoring, such as prefer-recent or boost-templates. The keywords will still be parsed, but they will have no effect.

Sorting options are currently available from the MediaWiki API by providing the srsort parameter.

Guidance:

Sorting options can be manually added to a search URL by adding &sort=order, for example:

Valid sort orders include:

URL supplement Описание
&sort=incoming_links_asc Lowest to highest number of incoming links. This is approximately from least to most popular.
&sort=incoming_links_desc Highest to lowest number of incoming links. This is approximately from most to least popular.
&sort=last_edit_asc From least recently to most recently edited
&sort=last_edit_desc From most to least recently edited
&sort=create_timestamp_asc From least to most recently created
&sort=create_timestamp_desc From most to least recently created
&sort=just_match A simple relevance sort based only on text matching
&sort=relevance A relevance sort taking into account many features of the document
&sort=random Randomized
&sort=none Unsorted, arbitrarily ordered lists. Preferred for large result sets.

Interface for advanced options

Advanced Search Interface

The AdvancedSearch extension adds an improved interface to the search page allowing the use of several options described above in a user-friendly manner. See here for the user manual.

См. также

Внешние ссылки

Примечания и комментарии

  1. Обратите внимание, что подзаголовок не является частью реального содержимого. Чтобы произвести поиск по содержимому странице, добавьте ?action=cirrusdump к URL.
  2. Stop words are rarely called for in CirrusSearch, except for when they are in certain kinds of phrases, as explained below.
  3. CirrusSearch parameters do not use a consistent way to handle these search terms.
  4. The same analyzer used to index the wikitext is also used to interpret the query.
  5. For example, common terms on this wiki, MediaWiki.org, are, redundantly, (searched):
    • udp2log or udp2log2 (though the extra 2 will affect ranking)
    • html2wt or wt2html
    • log2ip or ip2log

    There's test2wiki, wiki2xml, wiki2dict, apache2handler, apache2ctl, etc.

  6. CirrusSearch regex do not address the newline character directly, but a dot . will match a newline.
  7. A slow regex search cannot disable search, but can disable another's regex search, since there are only a limited number of regex searches allowed at a time.
  8. Prefix does not match on first-characters of fullpagenames, so you cannot search two namespaces at once just because they start with the same letters, such as both namespace and namespace talk in one query.
  9. For the formal definition see the Lucene grammar for regular expressions.
  10. Class RegExp, Lucene RegExp syntax