Redirects in Wikidata are basically the same as redirects on normal wiki pages. However, they have a slightly different meaning and intention.
The main reason why we need redirects is because we want to provide stable identifiers.
The merging of two items has been a common place task since Wikidata gain momentum as often two different people or bots create items representing the same topic or concept, thus the data from one needs to be moved into the other and the empty item removed.
The problem with this is that removing the empty item of course means that one of the two identifiers no longer points to the topic or concept that is represents. This is therefore not a stable identifier..
Redirects on regular wikis
On regular wikis redirects are not quite as important. Wiki page titles are not designed to be stable, pages can easily be moved and redirects in this case are used more for convenience than a necessity.
Of course redirects on wiki ages can also be used to provide multiple different names for a page. Within Wikidata this is done using Labels.
When redirects on Wikidata appeared
The first introduction of redirects to the Wikidata code base was as far as I can tell in commit e2ffe87c3f8995463b9b57192892632de7a6e3ec on 1 July 2014. This introduced an API module for creating redirects as well as the Interactor powering it.
This took a little while to be deployed and then it was technically possible for redirects to be created on Wikidata! Of course through the API only…
In August 2014 the Merge Gadget on Wikidata was poked to enable the creation of redirects after merging items, this can be seen in 152476498 and 154172795. As a result redirects were getting easier to create! Although as far as I know to this day this is the only way to create redirects through the UI.
Confusion by the community
Upon introduction of redirects to Wikidata many people seemed to get confused and did not see the point. This can mainly be seen in the request for comment of “Redirect vs deletion” which had a very close outcome. In fact one of the three points that were drawn from the discussion is in my opinion terrible (and has since been changed).
Deleting is however appropriate if an item has not been existed longer than 24 hours and if it’s clear that it’s not in use elsewhere.
This is terrible as 24 hours is really a long time! Many people could be using the identifier of an item within the first minutes of its creation, let alone hours.
Further issues open on Phabricator
- Creation of a SpecialPage for creating redirects
- Ability to create a redirect over a deleted or empty entity
- Try to detect and auto fix double redirects before they happen
- Make EntityView UI aware of redirects
- Include redirects in RDF rendering.
- Automatically create redirects when merging items (within the wbmergeitems module rather than gadget)
It would be interesting to see some data about the number of redirect and the speed at which they are being created, possibly in comparison to previous deletion rates.
The moral of the story, REDIRECT, REDIRECT, REDIRECT!!!!!