Wikidata Query Service/User Manual/yo - MediaWiki (2024)

Wikidata Query Service (WDQS) is a software package and public service designed to provide a SPARQL endpoint which allows you to query against the Wikidata data set.

This page or other relevant documentation pages will be updated accordingly; it is recommended that you watch them if you are using the service.

The Wikidata Query Service operates on a data set from Wikidata.org, represented in RDF as described in the RDF dump format documentation.

The service's data set does not exactly match the data set produced by RDF dumps, mainly for performance reasons; the documentation describes a small set of differences.

You can download a weekly dump of the same data from:

https://dumps.wikimedia.org/wikidatawiki/entities/

spo or "subject, predicate, object" is known as a triple, or commonly referred to in Wikidata as a statement about data.

The statement "The United States capital is Washington DC" consists of the subject "United States" (Q30), the predicate "capital is" (P36), and an object "Washington DC" (Q61). This statement can be represented as three URIs:

<http://www.wikidata.org/entity/Q30> <http://www.wikidata.org/prop/direct/P36> <http://www.wikidata.org/entity/Q61> .

Thanks to the prefixes (see below), the same statement can be written in a more concise form. Note the dot at the end to represent the end of the statement.

wd:Q30 wdt:P36 wd:Q61 .

The /entity/ (wd:) represents Wikidata entity (Q-number values).The /prop/direct/ (wdt:) is a "truthy" property — a value we would expect most often when looking at the statement.The truthy properties are needed because some statements could be "truer" than others.For example, the statement "The capital of U.S. is New York City" is true — but only in the historical context of the year 1790.WDQS uses rank to determine which statements should be used as "truthy".

In addition to the truthy statements, WDQS stores all statements (both truthy and not), but they don't use the same wdt: prefix.U.S. capital has three values: DC, Philadelphia, and New York.And each of these values have "qualifiers" - additional information, such as start and end dates, that narrows down the scope of each statement.To store this information in the triplestore, WDQS introduces an automatic "statement" subject, which is essentially a random number:

wd:Q30 p:P36 <random_URI_1> . # US "indirect capital" is <X><random_URI_1> ps:P36 wd:Q61 . # The X's "real capital value" is Washington DC<random_URI_1> pq:P580 "1800-11-17" . # The X's start date is 1800-11-17

spo is also used as a form of basic syntax layout for querying RDF data structures, or any graph database or triplestore, such as the Wikidata Query Service (WDQS), which is powered by Blazegraph, a high performance graph database.

Advanced uses of a triple (spo) even including using triples as objects or subjects of other triples!

The subjects and predicates (first and second values of the triple) must always be stored as URI.For example, if the subject is Universe (Q1), it will be stored as <https://www.wikidata.org/wiki/Q1>.Prefixes allow us to write that long URI in a shorter form: wd:Q1.Unlike subjects and predicates, the object (triple's third value) can be either a URI or a literal, e.g. a number or a string.

WDQS understands many shortcut abbreviations, known as prefixes. Some are internal to Wikidata, e.g. wd, wdt, p, ps, bd, and many others are commonly used external prefixes, like rdf, skos, owl, schema.

In the following query, we are asking for items where there is a statement of "P279 = Q7725634" or in fuller terms, selecting subjects that have a predicate of "subclass of" with an object of = "literary work".

The output variables:

PREFIX wd: <http://www.wikidata.org/entity/>PREFIX wds: <http://www.wikidata.org/entity/statement/>PREFIX wdv: <http://www.wikidata.org/value/>PREFIX wdt: <http://www.wikidata.org/prop/direct/>PREFIX wikibase: <http://wikiba.se/ontology#>PREFIX p: <http://www.wikidata.org/prop/>PREFIX ps: <http://www.wikidata.org/prop/statement/>PREFIX pq: <http://www.wikidata.org/prop/qualifier/>PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>PREFIX bd: <http://www.bigdata.com/rdf#># The below SELECT query does the following:# Selects all the items(?s subjects) and their labels(?label)# that have(WHERE) the statement(?s subject) has a direct property(wdt:) = P279 <subclasses of># with a value of entity(wd:) = Q7725634 <Literary Work># and optionally return the English labelsSELECT ?s ?label WHERE { ?s wdt:P279 wd:Q7725634 . OPTIONAL { ?s rdfs:label ?label filter (lang(?label) = "en"). } }

The service supports the following extensions to standard SPARQL capabilities:

Label service

You can fetch the label, alias, or description of entities you query, with language fallback, using the specialized service with the URI <http://wikiba.se/ontology#label>.The service is very helpful when you want to retrieve labels, as it reduces the complexity of SPARQL queries that you would otherwise need to achieve the same effect.

The service can be used in one of the two modes: manual and automatic.

In automatic mode, you only need to specify the service template, e.g.:

PREFIX wikibase: <http://wikiba.se/ontology#>SERVICE wikibase:label { bd:serviceParam wikibase:language "en" .}

and WDQS will automatically generate labels as follows:

In each case, the variable in ?NAME should be bound, otherwise the service fails.

Automatic mode only inspects the projection of the query – for instance, in SELECT ?aLabel (GROUP_CONCAT(?bLabel) AS ?bLabels), only the first label is recognized, and SELECT * is not supported by automatic mode at all.In such cases, you will need to use manual mode (see below).

You specify your preferred language(s) for the label with one or more of bd:serviceParam wikibase:language "language-code" triples.Each string can contain one or more language codes, separated by commas.WDQS considers languages in the order in which you specify them.If no label is available in any of the specified languages, the Q-id of the entity (without any prefix) is its label.

The Wikidata Query Service website automatically replaces [AUTO_LANGUAGE] with the language code of current user's interface. For example, if the user's UI is in French, the SPARQL's code bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en" will be converted to bd:serviceParam wikibase:language "fr,en" before being sent to the query service.

Example, showing the list of US presidents and their spouses:

SELECT ?p ?pLabel ?w ?wLabel WHERE { wd:Q30 p:P6/ps:P6 ?p . ?p wdt:P26 ?w . SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . } }

Try it!

In this example WDQS automatically creates the labels ?pLabel and ?wLabel for properties.

In the manual mode, you explicitly bind the label variables within the service call, but WDQS will still provide language resolution and fallback.Example:

 SELECT * WHERE { SERVICE wikibase:label { bd:serviceParam wikibase:language "fr,de,en" . wd:Q123 rdfs:label ?q123Label . wd:Q123 skos:altLabel ?q123Alt . wd:Q123 schema:description ?q123Desc . wd:Q321 rdf:label ?q321Label . } }

This will consider labels and descriptions in French, German and English, and if none are available, will use the Q-id as the label.

Geospatial search

The service allows to search for items with coordinates located within a certain radius of a central point or within a certain bounding box.

Search around point

Example:

# Airports within 100km from Berlin#defaultView:MapSELECT ?place ?placeLabel ?location ?dist WHERE { # Berlin coordinates wd:Q64 wdt:P625 ?berlinLoc . SERVICE wikibase:around { ?place wdt:P625 ?location . bd:serviceParam wikibase:center ?berlinLoc . bd:serviceParam wikibase:radius "100" . bd:serviceParam wikibase:distance ?dist. } # Is an airport FILTER EXISTS { ?place wdt:P31/wdt:P279* wd:Q1248784 } SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }} ORDER BY ASC(?dist)

Try it!

The first line of the around service call must have format ?item predicate ?location, where the result of the search will bind ?item to items within the specified location and ?location to their coordinates.The parameters supported are:

Search within box

Example of box search:

# Schools between San Jose, CA and Sacramento, CA#defaultView:MapSELECT * WHERE { wd:Q16553 wdt:P625 ?SJloc . wd:Q18013 wdt:P625 ?SCloc . SERVICE wikibase:box { ?place wdt:P625 ?location . bd:serviceParam wikibase:cornerSouthWest ?SJloc . bd:serviceParam wikibase:cornerNorthEast ?SCloc . } FILTER EXISTS { ?place wdt:P31/wdt:P279* wd:Q3914 }}

Try it!

or:

#Schools between San Jose, CA and San Francisco, CA#defaultView:MapSELECT ?place ?location WHERE { wd:Q62 wdt:P625 ?SFloc . wd:Q16553 wdt:P625 ?SJloc . SERVICE wikibase:box { ?place wdt:P625 ?location . bd:serviceParam wikibase:cornerWest ?SFloc . bd:serviceParam wikibase:cornerEast ?SJloc . } FILTER EXISTS { ?place wdt:P31/wdt:P279* wd:Q3914 }}

Try it!

Coordinates may be specified directly:

# Schools between San Jose, CA and Sacramento, CA#same as previous#defaultView:MapSELECT * WHERE {SERVICE wikibase:box { ?place wdt:P625 ?location . bd:serviceParam wikibase:cornerWest "Point(-121.872777777 37.304166666)"^^geo:wktLiteral . bd:serviceParam wikibase:cornerEast "Point(-121.486111111 38.575277777)"^^geo:wktLiteral . } FILTER EXISTS { ?place wdt:P31/wdt:P279* wd:Q3914 }}

Try it!

The first line of the box service call must have format ?item predicate ?location, where and the result of the search will bind ?item to items within the specified location and ?location to their coordinates.The parameters supported are:

wikibase:cornerSouthWest and wikibase:cornerNorthEast should be used together, as well as wikibase:cornerWest and wikibase:cornerEast, and cannot be mixed.If wikibase:cornerWest and wikibase:cornerEast predicates are used, then the points are assumed to be the coordinates of the diagonal of the box, and the corners are derived accordingly.

Extended functions

Distance function

The function geof:distance returns distance between two points on Earth, in kilometers.Example usage:

# Airports within 100km from BerlinSELECT ?place ?placeLabel ?location ?dist WHERE { # Berlin coordinates wd:Q64 wdt:P625 ?berlinLoc . SERVICE wikibase:around { ?place wdt:P625 ?location . bd:serviceParam wikibase:center ?berlinLoc . bd:serviceParam wikibase:radius "100" . } # Is an airport ?place wdt:P31/wdt:P279* wd:Q1248784 . SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . } BIND(geof:distance(?berlinLoc, ?location) as ?dist) } ORDER BY ?dist

Try it!

# Places around 0°,0° SELECT *{ SERVICE wikibase:around { ?place wdt:P625 ?location . bd:serviceParam wikibase:center "Point(0 0)"^^geo:wktLiteral . bd:serviceParam wikibase:radius "250" . } SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . ?place rdfs:label ?placeLabel } BIND(geof:distance("Point(0 0)"^^geo:wktLiteral, ?location) as ?dist) } ORDER BY ?dist

Try it!

Coordinate parts functions

Functions geof:globe, geof:latitude & geof:longitude return parts of a coordinate - globe URI, latitude and longitude accordingly.

Decode URL functions

Function wikibase:decodeUri decodes (i.e. reverses percent-encoding) given URI string. This may be necessary when converting Wikipedia titles (which are encoded) into actual strings. This function is an opposite of SPARQL encode_for_uri function.

# Example usage of wikibase:decodeUri functionSELECT DISTINCT * WHERE { ?el wdt:P31 wd:Q5. ?webRaw schema:about ?el; schema:inLanguage "ru"; schema:isPartOf <https://ru.wikipedia.org/>. BIND(URI(wikibase:decodeUri(STR(?webRaw))) AS ?webHyperlink) . BIND(wikibase:decodeUri(STR(?webRaw)) AS ?webString) .}LIMIT 20

Automatic prefixes

Most prefixes that are used in common queries are supported by the engine without the need to explicitly specify them.

Extended dates

The service supports date values of type xsd:dateTime in the range of about 290B years in the past and in the future, with one-second resolution.WDQS stores dates as the 64-bit number of seconds since the Unix epoch.

Blazegraph extensions

Warning:

Blazegraph platform on top of which WDQS is implemented has its own set of SPARQL extension.Among them several graph traversal algorithms which are documented on Blazegraph Wiki, including BFS, shortest path, CC and PageRank implementations.

Please also refer to the Blazegraph documentation on query hints for information about how to control query execution and various aspects of the engine.

There is no documentation in the BlazeGraph wiki about the bd:sample extension.It's documented only in a comment in the code.

Federation

We allow SPARQL Federated Queries to call out to a selected number of external databases.Please see the full list of federated endpoints on the dedicated page.

Example federated query:

• Items used: Félix Lope de Vega y Carpio (Q165257)

• Properties used: BVMC person ID (P2799)

SELECT ?workLabel WHERE { wd:Q165257 wdt:P2799 ?id BIND(uri(concat("https://data.cervantesvirtual.com/person/", ?id)) as ?bvmcID) SERVICE <http://data.cervantesvirtual.com/openrdf-sesame/repositories/data> { ?bvmcID <http://rdaregistry.info/Elements/a/otherPFCManifestationOf> ?work . ?work rdfs:label ?workLabel }}

Try it!

Please note that the databases that the federated endpoints serve use ontologies that may be very different from the Wikidata one. Please refer to the owner documentation links to learn about the ontologies and data access to these databases.

MediaWiki API

MediaWiki API Service allows to call out to MediaWiki API from SPARQL, and receive the results from inside the SPARQL query.Example (finding category members):

• Items used: parking lot (Q6501349)

• Properties used: topic's main category (P910)

SELECT * WHERE { wd:Q6501349 wdt:P910 ?category . ?link schema:about ?category; schema:isPartOf <https://en.wikipedia.org/>; schema:name ?title . SERVICE wikibase:mwapi { bd:serviceParam wikibase:api "Generator" . bd:serviceParam wikibase:endpoint "en.wikipedia.org" . bd:serviceParam mwapi:gcmtitle ?title . bd:serviceParam mwapi:generator "categorymembers" . bd:serviceParam mwapi:gcmprop "ids|title|type" . bd:serviceParam mwapi:gcmlimit "max" . # out ?subcat wikibase:apiOutput mwapi:title . ?ns wikibase:apiOutput "@ns" . ?item wikibase:apiOutputItem mwapi:item . }}

Try it!

Wikimedia runs the public service instance of WDQS, which is available for use at http://query.wikidata.org/.

The runtime of the query on the public endpoint is limited to 60 seconds.That is true both for the GUI and the public SPARQL endpoint.

GUI

The GUI at the home page of http://query.wikidata.org/ allows you to edit and submit SPARQL queries to the query engine.The results are displayed as an HTML table.Note that every query has a unique URL which can be bookmarked for later use.Going to this URL will put the query in the edit window, but will not run it - you still have to click "Execute" for that.

One can also generate a short URL for the query via a URL shortening service by clicking the "Generate short URL" link on the right - this will produce the shortened URL for the current query.

The "Add prefixes" button generates the header containing standard prefixes for SPARQL queries.The full list of prefixes that can be useful is listed in the RDF format documentation.Note that most common prefixes work automatically, since WDQS supports them out of the box.

The GUI also features a simple entity explorer which can be activated by clicking on the "🔍" symbol next to the entity result.Clicking on the entity Q-id itself will take you to the entity page on wikidata.org.

Default views

Main article: wikidata:Special:MyLanguage/Wikidata:SPARQL query service/Wikidata Query Help/Result Views

If you run the query in the WDQS GUI, you can choose which view to present by specifying the tag: #defaultView:viewName at the beginning of the query.

Display a title

If you run the query in the WDQS GUI, you can display a title on top of the results by specifying the tag: #title: String you want to display at the beginning of the query.

SPARQL endpoint

POST requests can alternatively accept the query in the body of the request, instead of the URL, which allows running larger queries without hitting URL length limits. (Note that the POST body must still include the query= prefix (that is, it should be query=(SPARQL_query) rather than just (SPARQL query)), and the SPARQL query must still be URL-escaped.)

The result is returned as XML by default, or as JSON if either the query parameter format=json is included in the URL, or the header Accept: application/sparql-results+json is provided with the request.

It is recommended to use GET for smaller queries and POST for larger queries, as POST queries are not cached.

Supported formats

The following output formats are currently supported by the SPARQL endpoint:

Query limits

There is a hard query deadline configured which is set to 60 seconds.There are also following limits:

Clients exceeding the limits above are throttled with HTTP code 429.Use Retry-After header to see when the request can be repeated.If the client ignores 429 responses and continues to produce requests over the limits, it can be temporarily banned from the service.Clients who don’t comply with the User-Agent policy may be blocked completely – make sure to send a good User-Agent header.

Every query will timeout when it takes more time to execute than this configured deadline.You may want to optimize the query or report a problematic query here.

Also note that currently access to the service is limited to 5 parallel queries per IP. The above limits are subject to change depending on resources and usage patterns.

Explain Query

Blazegraph allows to show query analysis that explains how the query has been parsed and which optimizations were applied.To see this information, add explain=details parameter to the query string, for example: https://query.wikidata.org/sparql?query=SELECT%20?dob%20WHERE%20{wd:Q42%20wdt:P569%20?dob.}&explain=details.

Namespaces

The data on Wikidata Query Service contains the main namespace, wdq, to which queries to the main SPARQL endpoint are directed, and other auxiliary namespaces, listed below.To query data from different namespace, use endpoint URL https://query.wikidata.org/bigdata/namespace/NAMESPACENAME/sparql.

Categories

Please see full description on Categories documentation page.

DCAT-AP

Example query to retrieve data:

PREFIX dcat: <http://www.w3.org/ns/dcat#>PREFIX dct: <http://purl.org/dc/terms/>SELECT ?url ?date ?size WHERE { <https://www.wikidata.org/about#catalog> dcat:dataset ?dump . ?dump dcat:distribution [ dct:format "application/json" ; dcat:downloadURL ?url ; dct:issued ?date ; dcat:byteSize ?size ] .}

Linked Data Fragments endpoint

We also support querying the database using Triple Pattern Fragments interface.This allows to cheaply and efficiently browse triple data where one or two components of the triple is known and you need to retrieve all triples that match this template.See more information at the Linked Data Fragments site.

The interface can be accessed by the URL: https://query.wikidata.org/bigdata/ldf.This service is implemented on the top of Blazegraph database, so it will have the same lag as the Query Service.Example requests:

• https://query.wikidata.org/bigdata/ldf?predicate=http%3A%2F%2Fwww.wikidata.org%2Fprop%2Fdirect%2FP212&object=%22978-0-262-03293-3%22 All triples that have 978-0-262-03293-3 as the value for ISBN-13 (P212). The following shell command uses curl to build the same URL and obtain the same data.

$ curl \ --get \ -H 'Accept: application/rdf+xml' \ --data-urlencode 'predicate=http://www.wikidata.org/prop/direct/P212' \ --data-urlencode 'object="978-0-262-03293-3"' \ 'https://query.wikidata.org/bigdata/ldf'

Note that only full URLs are currently supported for the subject, predicate and object parameters.

By default, HTML interface is displayed, however several data formats are available, defined by Accept HTTP header.

The data is returned in pages, page size being 100 triples.The pages are numbered starting from 1, and page number is defined by page parameter.

As the service is open source software, it is also possible to run the service on any user's server, by using the instructions provided below.

If you plan to run the service against non-Wikidata Wikibase instance, please see further instructions.

Installing

In order to install the service, it is recommended that you download the full service package as a ZIP file, e.g. from Maven Central, with group ID org.wikidata.query.rdf and artifact ID "service" , or clone the source distribution at https://github.com/wikimedia/wikidata-query-rdf/ and build it with "mvn package".The package ZIP will be in the dist/target directory under service-VERSION-dist.zip.

The package contains the Blazegraph server as a .war application, the libraries needed to run the updater service to fetch fresh data from the wikidata site, scripts to make various tasks easier, and the GUI in the gui subdirectory.If you want to use the GUI, you will have to configure your HTTP server to serve it.

By default, only the SPARQL endpoint at http://localhost:9999/bigdata/namespace/wdq/sparql is configured, and the default Blazegraph GUI is available at http://localhost:9999/bigdata/.Note that in the default configuration, both are accessible only from localhost.You will need to provide external endpoints and an appropriate access control if you intend to access them from outside.

Using snapshot versions

If you want to install an un-released snapshot version (usually this is necessary if released version has a bug which is fixed but new release is not available yet) and do not want to compile your own binaries, you can use either:

Loading data

Warning:

As of 2020, in Wikimedia servers it will take about 12 days to get all data in the dump imported, and another 12 days to make the query service catching up the lag.

Further install procedure is described in detail in the Getting Started document which is part of the distribution, and involves the following steps:

Loading categories

If you also want to load category data, please do the following:

1. Create namespace, e.g. categories: createNamespace.sh categories
2. Load data into it: forAllCategoryWikis.sh loadCategoryDump.sh categories

Note that these scripts only load data from Wikimedia wikis according to Wikimedia settings.If you need to work with other wiki, you may need to change some variables in the scripts.

Scripts

The following useful scripts are part of the distribution:

munge.sh

Pre-process data from RDF dump for loading.

Example:

./munge.sh -c 50000 -f data/wikidata-20150427-all-BETA.ttl.gz -d data -l en -s

loadData.sh

Load processed data into Blazegraph. Requires curl to be installed.

Example:

./loadData.sh -n wdq -d `pwd`/data

runBlazegraph.sh

Run the Blazegraph service.

Example:

./runBlazegraph.sh

Inside the script, there are two variables that one may want to edit:

# Q-id of the default globeDEFAULT_GLOBE=2# Blazegraph HTTP User Agent for federationUSER_AGENT="Wikidata Query Service; https://query.wikidata.org/";

Also, the following environment variables are checked by the script (all of them are optional):

runUpdate.sh

Run the Updater service.

It is recommended that the settings for the -l and -s options (or absence thereof) be the same for munge.sh and runUpdate.sh, otherwise data may not be updated properly.

Example:

./runUpdate.sh

Also, the following environment variables are checked by the script (all of them are optional):

Updater options

The following options works with Updater app.

They should be given to the runUpdate.sh script as additional options after --, e.g.: runUpdate.sh -- -v.

Configurable properties

The following properties are configurable via adding them to the script run command in the scripts above:

Below are features which are currently not supported:

If you notice anything wrong with the service, you can contact the Discovery team by email on the list discovery@lists.wikimedia.org or on the IRC channel #wikimedia-discovery.

• RDF dump format