Wikidata Query Service/User Manual/es

Wikidata Query Service (WDQS) es un paquete de software y servicio público diseñado para proporcionar un endpoint en lenguaje SPARQL que te permite consultar los datos de Wikidata.

Esta página u otras páginas de documentación relevantes se actualizarán cuando corresponda, se recomienda que las mires si estás utilizando el servicio.

Puedes ver ejemplos de consultas SPARQL en la página de ejemplos.

Datos
El  Wikidata Query Service (servicio de consultas de Wikidata) opera en un conjunto de datos de Wikidata.org, representado en RDF como se describe en la documentación del formato de volcado RDF.

El conjunto de datos del servicio no coincide exactamente con el conjunto de datos producido por los volcados RDF, principalmente por razones de rendimiento. La documentación describe un pequeño conjunto de diferencias.

Puedes descargar un volcado semanal de los mismos datos desde:

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

Conceptos básicos: Comprender el SPO (Sujeto, Predicado, Objeto) también conocido como la Terna Semántica
Un SPO o «sujeto, predicado, objeto» es también conocido como una terna o tripleta semántica o, como comúnmente se le menciona en Wikidata, como una declaración (statement) de datos.

La declaración «Los Estados Unidos tienen como capital Washington DC» consta del sujeto «Los Estados Unidos» (Q30), del predicado «tienen como capital» (P36) y del objeto «Washington DC» (Q61). Esta declaración se puede representar como tres URIː

Gracias a los prefijos (ver más abajo), la misma declaración se puede escribir en una forma más concisa. Fíjate en el punto al final para representar el final de la declaración.

El /entity/ (wd:) representa a la entidad de Wikidata (los valores almacenados con el número Q). El /prop/direct/ (wdt:) es una propiedad "verdadera": el valor que esperaríamos con mayor frecuencia cuando observamos la declaración. Las propiedades verdaderas son necesarias puesto que algunas declaraciones podrían ser "más verdaderas" que otras. Por ejemplo, la declaración «Los Estados Unidos tienen como capital la ciudad de Nueva York» también es cierta, pero solo en el contexto histórico del año 1790. WDQS utiliza rangos para determinar qué declaraciones deben utilizarse como "verdaderas".

Además de las declaraciones verdaderas, WDQS almacena todas las declaraciones (las verdaderas y las que no), pero estas no usan el mismo prefijo wdt:. La capital de EE.UU. tiene tres valores: Washington DC, Filadelfia y Nueva York. Y cada uno de estos valores tienen "calificadores", información adicional, como las fechas de inicio y de fin, que limitan el alcance de cada declaración. Para almacenar esta información en la tripleta, WDQS añade un sujeto de "declaración" automáticamente, que es esencialmente un número aleatorio.

Mira el tutorial de SPARQL sobre calificadores para más información.

Spo también es usado como una forma de sintaxis básica para consultar RDF estructuras de datos o cualquier bases de datos de grafos o triplestore, tal como el servicio Query de Wikidata (WDQS por sus siglasen inglés), el cual es impulsado por Blazegraph, una base de datos de grafos de alto rendimiento.

¡El uso avanzado de un triple (spo) aun incluye uso de triples como objetos o sujetos de otros triples!

Básicos-Prefijos comprensivos
Los sujetos y predicados (primeros y segundos valores del triple) siempre debe ser almacenado como URI. Por ejemplo, si el tema es Universe (Q1), será almacenado como    . Los prefijos nos permiten escribir esa url larga de una manera más corta: wd:Q1. A diferencia de los sujetos y predicados, el objeto (tercer valor del triple) también puede ser una URI, por ejemplo, un número o una cadena.

El servicio Query de Wikidata entiende muchas abreviaturas, conocidas como prefijos. Algunas son internas a Wikidata, por ejemplo wd, wdt, p, ps, bd, y muchas otras son comunmente usados como prefijos externos, como "rdf", "skos", "owl" o "schema".

En el siguiente query, estamos solicitando items donde hay una declaración de "P279 = Q7725634" o, a grandes rasgos, seleccionando temas que tienen un predicado de "subclase de" con un objeto de "obra literaria".

Las variables de salida son:

Extensiones
El servicio soporta las siguientes extensiones de las capacidades estándar de SPARQL:

Servicio de etiqueta
Puedes recuperar la etiqueta, el "alias" o la descripción de las entidades de tu query, con el respaldo del idioma, usando el servicio especializado con la URI .

El servicio puede ser usado en uno de dos modos: manual y automático.

En modo automático, tú solo necesitas especificar la plantilla de servicio. Por ejemplo:

Geospatial search [ edit ]
The service allows to search for items with coordinates located within certain radius of the center of within certain bounding box.

Search around point [ edit ]
Example:

La primera línea de la llamada de servicio  debe tener el formato     , donde el resultado de la búsqueda va a unir el   a los items dentro de la locación especificada y   a sus coordenadas. Los parámetros de apoyo son:

Búsqueda dentro de la caja
Ejemplo de la búsqueda de cajas:

o:

Las coordenadas pueden ser especificadas directamente:

La primera linea de la llamada de servicio  debe tener el formato     , donde el resultado de la búsqueda va a unir el   a los intems dentro de la locación especificada y   a sus coordenadas. Los parámetros soportados son:

y  deben usarse juntos, así como   y , y no deben ser mezclado. Si se usan los predicados  y , entonces los puntos son asumidos para ser las coordenadas de la diagonal de la caja, y en consecuencia las esquinas se derivan.

Función de distancia
La función  regresa la distancia entre dos puntos de la Tierra, en kilómetros. Ejemplo de uso:

Funciones de piezas de coordenadas
Las funciones,   y   devuelven las partes de una URI de coordenada-globo, y en consecuencia la latitud y longitud.

Descodificar funciones de URL
Function  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.

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  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
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.

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:

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
Please see full description on MediaWiki API Service documentation page.

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):

Wikimedia service
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. If you need to run longer queries, please contact the Discovery team.

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 a comment:  at the beginning of the query.

SPARQL endpoint
SPARQL queries can be submitted directly to the SPARQL endpoint with a GET or POST request to.

GET requests have the query specified in the URL, in the format, e.g..

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  prefix (that is, it should be   rather than just  ), 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  is included in the URL, or the header   is provided with the request.

The JSON format is standard SPARQL 1.1 Query Results JSON Format.

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:


 * One client (user agent + IP) is allowed 60 seconds of processing time each 60 seconds
 * One client is allowed 30 error queries per minute

Clients exceeding the limits above are throttled with HTTP code. Use  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  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  parameter to the query string, for example:.

Namespaces
The data on Wikidata Query Service contains the main namespace,, 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.

DCAT-AP [ edit ]
The DCAT-AP data for Wikidata is available as SPARQL at https://dcatap.wmflabs.org/ endpoint.

The SPARQL endpoint for accessing it is: https://dcatap.wmflabs.org/sparql

The source for the data is: https://dumps.wikimedia.org/wikidatawiki/entities/dcatap.rdf

Example query to retrieve data:

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:. Example requests:


 * https://query.wikidata.org/bigdata/ldf?subject=http%3A%2F%2Fwww.wikidata.org%2Fentity%2FQ146 - all triples with subject


 * https://query.wikidata.org/bigdata/ldf?subject=&predicate=http%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23label&object=%22London%22%40en - all triples that have English label "London"

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

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

Standalone service
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.

The hardware recommendations can be found in Blazegraph documentation.

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  and artifact ID " ", 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  directory under.

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  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:
 * https://github.com/wikimedia/wikidata-query-deploy - deployment repo containing production binaries. Needs  working. Check it out and do " ".
 * Archiva snapshot deployments at https://archiva.wikimedia.org/#artifact/org.wikidata.query.rdf/service - choose the latest version, then Artifacts, and select the latest package for download.

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


 * 1) Download recent RDF dump from https://dumps.wikimedia.org/wikidatawiki/entities/ (the RDF one is the one ending in  ).
 * 2) Pre-process data with the   script. This creates a set of TTL files with preprocessed data, with names like , etc. See options for the script below.
 * 3) Start Blazegraph service by running the   script.
 * 4) Load the data into the service by using  . Note that loading data is usually significantly slower than pre-processing, so you can start loading as soon as several preprocessed files are ready. Loading can be restarted from any file by using the options as described below.
 * 5) After all the data is loaded, start the Updater service by using.

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


 * 1) Create namespace, e.g.  :
 * 2) Load data into it:

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.

Ejemplo:

loadData.sh
Load processed data into Blazegraph. Requires  to be installed.

Ejemplo:

runBlazegraph.sh
Run the Blazegraph service.

Ejemplo:

Inside the script, there are two variables that one may want to edit: 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  and   options (or absence thereof) be the same for munge.sh and runUpdate.sh, otherwise data may not be updated properly.

Ejemplo:

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  script as additional options after , e.g.:.

This list may be incomplete, use  option to get the full list of available options.

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

Missing features
Below are features which are currently not supported:


 * Redirects are only represented as owl:sameAs triple, but do not express any equivalence in the data and have no special support.

Contacts
If you notice anything wrong with the service, you can contact the Discovery team by email on the list  or on the IRC channel.

Bugs can also be submitted to and tracked on the Discovery Phabricator board.

Ve también

 * WDQ to SPARQL syntax translator
 * SPARQL Query examples
 * Discovery team
 * WDQS Implementation notes
 * An introduction to SPARQL query syntax