Month: August 2025

Wikidata, instance of and subclass of through time (P31 & P279)

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Last month I looked at all Wikimedia Commons revisions and managed to generate some data and graphs for the usage of depicts statements since they were introduced on the project.

This month, I have applied the same analysis on Wikidata but looking at instance of and subclasses of items. A slightly bigger data set, however essentially the same process.

This will enable easy updating, of various pie charts that have been published over the years, such as

In future, this could be easily adapted to show per Wikipedia project graphs, such as those that are currently at Wikidata:Statistics/Wikipedia

Method

The details of the method can be seen in code in my previous post about depicts statements, and this mostly stays the same.

In words:

  • Look at every revision of Wikidata ever
  • Parse the JSON to determine what values there are for P31 and P279 for each revision
  • Find the latest revision of each item in each given month, and thus find the state of all items in that month
  • Plot the data by number of items that are P31 or P279 of each value item

There are some minor defects to this logic currently that could be cleaned up with future iterations:

  • Deleted items will continue being counted, as I don’t consider the point items are deleted
  • Things will be double counted in this data, as 1 item may have multiple P31 and P279 values, and I don’t try to join these into higher level concept at all

We make an OTHER and UNALLOCATED count as part of the final data summarization. OTHER accounts for things that have not made it into the top 20 items by count, and UNALLOCATED means that we didn’t have a P31 or P279 value in the latest revision.

2025

For August 2025 (or at least part way through it), this is the current state of Wikidata per the above method.

You can now find a PNG of this pie chart on Wikimedia Commons https://commons.wikimedia.org/wiki/File:Wikidata_P31_%26_P279_analysis_August_2025.png

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Online RDS column type modification, using pt-online-schema-change from EC2

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I’m using percona-tools to do an online schema modification today, and thought I would document the process, especially as even the installation guides seem to be badly linked, out of date, and did not work out of the box…

EC2 instance

This is all running on a t3.micro EC2 instance with Ubuntu. I deliberately didn’t go with Amazon Linux, as I wanted to be able to use apt. For simplicities’ sake, I’ll be using the EC2 Instance Connect feature, which allows connection to a session in a web browser! (although the copy and paste via this is annoying)

This instance of course also needs access to your MySQL server, in this case an RDS instance. So I’ll go ahead and add it to the security group.

Percona toolkit

Percona Toolkit is a powerful open-source collection of advanced command-line tools designed to help MySQL and MariaDB DBAs perform tasks like online schema changes, replication troubleshooting, and data auditing safely and efficiently.

It’s used a Wikimedia for online database migrations (the reason I know about it), however I have never actually used it myself!

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What is Wikibase “Federated Properties” in 2025

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I recently wrote a post looking at the history of the Wikibase “Federated Properties” feature. While at Wikimania 2025 the topic of federation came up a few times, particularly given the current discussions ongoing on the Wikidata project chat page including discussions about wikicite, and the recent Wikidata graph split.

All the code for the “Federated Properties” feature still exists in Wikibase code, despite a ticket being open on phabricator to potentially delete it. And it turns out that the configuration for it still exists on wikibase.cloud too, where the feature was initially presented to the communities to try out.

So with a little bit of sneaky “hacking”, I can try to summarize the current / final state of the “Federated Properties” feature, after development during the MVP stopped some years ago.

This also means you can still try out the feature on your own wiki using the setting.

$wgWBRepoSettings['federatedPropertiesEnabled'] = true;

Creating a local property

Firstly, we need a property, and the creation workflow is exactly the same as on a normal Wikibase.

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What was Wikibase “Federated Properties”

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The “Federated Properties” feature allows / allowed a local Wikibase instance to access and utilise properties directly from a remote Wikibase, primarily Wikidata. Its primary purpose is to enable partial federation between a local Wikibase and Wikidata, broadening the base of available data without needing to create a property set from scratch.

I’m split between using the present and past tense here, as all of this code still exists within the Wikibase extension, however no one has used it since 2022, and it certainly doesn’t seem to be on the short or medium term (or maybe even long term) roadmaps.

This overview comes from the Wikibase – Federated Properties Phabricator project, which I’ll quote the whole of here for prosperity.

Federated Properties v2 (2021)
An initiative to give users the ability to access remote properties from their local Wikibase and use them in combination with custom local properties. The primary use case is enabling partial federation between a Wikibase and Wikidata. This version of the feature will allow you to:

  • Opt-in to use Wikidata’s properties in addition to your own custom local properties
  • Create and view statements about local entities that contain both local and federated properties
  • Query your Wikibase using both local and federated properties

Federated Properties v1 (2020-2021)
An initiative to give users the ability to access remote properties from their local Wikibase (no local properties were possible in this MVP). This version was launched in the Wikibase Spring Release in May 2021.

As far as I remember, the project died with v2, and I don’t even recall if v2 really saw the light of day outside WMDE internal testing and or hidden testing on wikibase.cloud.

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