Thanks, Jaime, for your recommendation.

If I understand the result of [1] correctly, there are around 3.5 million pages with a GeoNames property specified on Wikidata. I'm sure some of them are redirects, or not cities, etc. But still, going through millions of pages through API calls of 1000 at a time is cumbersome and inefficient. (The example you gave takes 20 seconds to run; that would mean a total of 20 * 3.5 * 1000 seconds which is like 19 hours, assuming no lag or error).

However, what you suggested gave me an idea: I can take a look at the code for the Api itself (I guess it is at [2]) and figure out how the query is written there, then try to write a similar query on my own. If I figure it out, I will report back here.

Huji

[1] https://quarry.wmflabs.org/query/25418
[2] https://phabricator.wikimedia.org/diffusion/EWBA/browse/master/client/includes/Api/ApiPropsEntityUsage.php

On Tue, Mar 13, 2018 at 5:39 AM, Jaime Crespo <jcrespo@wikimedia.org> wrote:

I am not 100% sure there is a perfect way to do what you want by querying the metadata databases (I assume that is what you mean with query)- I don't think that data is metadata, but content itself, which is not on the metadata databases.

Calling the wikidata query service is probably what you want:

<https://query.wikidata.org/#SELECT%20%3Fitem%20%3FitemLabel%20%3Fgeoname%0AWHERE%20%7B%0A%09%3Fitem%20wdt%3AP1566%20%3Fgeoname%20.%0A%09SERVICE%20wikibase%3Alabel%20%7B%20bd%3AserviceParam%20wikibase%3Alanguage%20%22%5BAUTO_LANGUAGE%5D%2Cen%22%20%7D%0A%7D%0ALIMIT%201000%20OFFSET%201000>

Note the LIMIT and OFFSET that will let you iterate over the dataset (a where close would be faster).

There is a way to get results, which is iterating over:
<https://www.wikidata.org/w/index.php?title=Special:WhatLinksHere/Property:P1566&hidetrans=1&hideredirs=1>

That is a standard mediawiki api query, you will also find this on the pagelinks table, but you should check every page you get afterwards (by retrieving its contents), as it could include false positives or be behind on updates.

On Sun, Mar 11, 2018 at 3:44 PM, Huji Lee <huji.huji@gmail.com> wrote:

Hello,

I need help writing a query that I would like to run on the Clouds. The goal of the query is to retrieve the following information from wikidatawiki_p:

* Find all pages that have a claim for the property P1566, for example see https://www.wikidata.org/wiki/Q2113430

* Find out what is the value of their P1566 property (in this case, 18918)

Output format should be like this:

page_id       entity            property_value
2039804      Q2113430     18918
...

Thanks in advance,

Huji

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--

Jaime Crespo

<http://wikimedia.org>

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