Extension:Cognate

The Cognate extension creates a central store where the page titles for a group of sites are stored. It can then generate interwiki links across wiki projects in cases where the titles are the same. It was developed to solve the "Centralize interwiki language links for Wiktionary" task.

"Cognate" is a linguistic concept, referring to words in different languages developed from the same origin. This means that this extension is misnamed—since this extension links pages with the same title across wikis, a proper name would be “Homograph”.

Assumptions and restrictions

 * Pages must be in one of the standard MediaWiki namespaces.
 * Page titles are the same across languages (with some simple normalization applied).
 * Sites should have the same interwiki structure for language links.
 * Pages should not contain inter language links in wikitext as these will override the link provided by Cognate.
 * Unexpected hash conflicts are unlikely but could occur, and would result in unexpected language links.

Title Normalization
Very simple title normalization (reduction to ASCII) occurs within the extension. This can be seen in the StringNormalizer class.

Initially the amount of normalization is very small. Requests can be made to expand this and will be added on a case by case basis.

Title Hashing
Titles are hashed using sha256. This can be seen in the StringHasher class.

Part of the hash is then stored in the database in a BIG_INT field for efficient lookups.

There are roughly 18,446,744,073,709,551,615 possible values.

Matching Hashes
As titles that require links are assumed to be the same post normalization, they will result in the same hash and thus the same Int stored in the database.

Some sample data might look as follows when loading the "Foo..." page on enwiktionary.

Overwriting
It is possible to overwrite the automatic links provided by Cognate, simply by adding one or more interwiki links in the page.

That also means that to make Cognate work when the extension is deployed, the pages should not contain inter language links in their wikitext.

Testing


The extension can be tested on beta wiktionary sites:


 * https://en.wiktionary.beta.wmflabs.org/wiki/Wiktionary:Main_Page
 * https://de.wiktionary.beta.wmflabs.org/wiki/Hauptseite
 * https://he.wiktionary.beta.wmflabs.org/wiki/%D7%A2%D7%9E%D7%95%D7%93_%D7%A8%D7%90%D7%A9%D7%99

These sites are linked together using the Cognate extension with added interwiki sorting provided by the InterwikiSorting extension.

Installation

 * Populate the sites table by running the populateCognateSites.php maintenance script. Sites must already exist in the MediaWiki sites table with the correct groupings.

php ./maintenance/populateCognateSites.php --site-group=wiktionary


 * Populate the page and title tables by running the populateCognatePages.php maintenance script.

php ./maintenance/populateCognatePages.php