What are the MediaWiki functions which alter categories in database?

I'm currently working on a project to change the category administration from Mediawiki to neo4j. (To store categories and relations with neo4j instead of the Mediawiki-MySQL DB)

I didn't found a special hook from Mediawiki for the category creation (When the category and categorylinks are stored to db). Now I try to replace the functions that insert, update and select the cate开发者_运维问答gory table (MySQL).

Unfortunately I don't find a starting point from where to begin. Which file from Mediawiki should be altered? Any other suggestions?

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The main update is done in includes/LinksUpdate.php. The relevant hooks are LinksUpdate and LinksUpdateComplete. There seem to be one or two other places where a sortkey is updated or a record is deleted. The reads from the table seem to be done all over the place as needed.