Hi!

Hi all, I am building a Question Answering System for Wikidata (I will put the demo live in May) and would like to be able to ask quesitons like "Give me the cities in Alaska". To query Wikidata I am using the Wikidata SPARQL endpoint.

The SPARQL query for this question looks the following way [0]:

SELECT DISTINCT ?x ?xLabel { # All things in Alaska ?x (wdt:P131+ | wdt:P276) wd:Q797 . # All cities ?x ((wdt:P106 | wdt:P39 | wdt:P31) / wdt:P279*) wd:Q515 . SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . } }

I'm not sure why you are using P106 or P39 for cities. If some data has it, it's almost certainly an error - city can not hold a position or have an occupation. Using P276 is usually an error too.

For the query, I'd suggest this one: http://tinyurl.com/m5dtwax

The 'all cities' part of your query seems strange. If you replace it with a simple 'instance of city' - ?x wdt:P31 wd:Q515 . it returns 145 results in 341ms. http://tinyurl.com/m4ffatg Why would you ask for things that have 'occupation' or 'position' with value city?

Also, I'm not familiar with the use of the '/' in that line of the query. My experience with that is as a mathematical operator. What is it supposed to be doing?

On Wed, Apr 5, 2017 at 10:00 AM, Anatoly Zelenin anatoly@zelenin.de wrote:

Hi all, I am building a Question Answering System for Wikidata (I will put the demo live in May) and would like to be able to ask quesitons like "Give me the cities in Alaska". To query Wikidata I am using the Wikidata SPARQL endpoint.

The SPARQL query for this question looks the following way [0]:

SELECT DISTINCT ?x ?xLabel { # All things in Alaska ?x (wdt:P131+ | wdt:P276) wd:Q797 . # All cities ?x ((wdt:P106 | wdt:P39 | wdt:P31) / wdt:P279*) wd:Q515 . SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . } }

As it needs to join over two very large sets (the set of all cities and the set of all things in Alaska) the query times out. Do you have an idea how I could write the query without getting a timeout? Thank you ;)

[0] https://query.wikidata.org/#SELECT%20DISTINCT%20%3Fx%20% 3FxLabel%0A%7B%0A%3Fx%20%28wdt%3AP131%2B%20%7C%20wdt% 3AP276%29%20wd%3AQ797%20.%0A%3Fx%20%28%28wdt%3AP106%20%7C% 20wdt%3AP39%20%7C%20wdt%3AP31%29%20%2F%20wdt%3AP279%2a%29% 20wd%3AQ515%20.%0ASERVICE%20wikibase%3Alabel%20%7B%0Abd% 3AserviceParam%20wikibase%3Alanguage%20%22en%22%20.%0A%7D%0A%7D

-- Best, Anatoly Zelenin

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