|It is proposed that this informational page become a policy or guideline. Please see the discussion on its talk page or the project chat.
The following is a proposed Wikidata policy or guideline. The proposal may still be in development, under discussion, or in the process of gathering consensus for adoption.
|This page in a nutshell: When merging items, check the subjects are the same, move the sitelinks, copy any missing properties, propose the empty item for deletion. Ask if you are unsure.|
A merge is performed if two or more items are about the same subject. It can be done either manually or automatically by moving sitelinks and properties into one item, and then requesting the deletion of the obsolete item(s).
This guideline explains the stages to be followed in order to perform a manual merge. It also explains how to enable automatic merges by activating the "Merge" gadget in your preferences.
- 1 Glossary
- 2 Merge: semi-automatic process
- 3 Another semi-automatic process
- 4 Manual merge: step by step
- 5 Where can I find items to merge?
- 6 See also
- Recipient item: the item you are merging to.
- Obsolete item: an item you are merging from.
Merge: semi-automatic process
Merge.js is a gadget by Ebraminio that helps moving sitelinks, labels, descriptions, aliases, and statements with references. After this, it can send that item to WD:RFD or (for admins only) delete the item with an auto-generated reason.
To enable this function, open Preferences, select Gadgets, and tick the merge gadget. To use it, open either the recipient or obsolete item, go to the drop-down menu to the left of "Search" in the top bar, select "Merge it with...", and enter the ID of the other item into the merge wizard. Be sure to tick the relevant boxes before clicking "Merge".
Bear in mind, you should always check that the items are the same, since Merge.js simply performs merging that you select to be done. However, the merge process is terminated if an interwiki conflict is found.
Another semi-automatic process
A newer version of Wikibase also supports merging performed on a client wiki. This is the easiest way to merge two items, but it is only possible if one item contains exactly one link.
If you want to merge two such items, go to the page linked with the first single-link-item, click on "Edit links", and connect the page with a page linked with the second item. If there is no conflict, the merge is performed; otherwise a warning appears. After that, you can request deletion of the empty item (see Request deletion section).
Manual merge: step by step
Check to be sure
Make sure that the items are indeed about the same subject. There could be subtle differences meaning that the two items have been segregated up to this point.
- de:Baum (tree)
- The items are about the same subject and so should be merged.
- de:Eichen (oak tree)
- The items are about similar but subtly different subjects and so should remain separate.
If you are unsure, due to having trouble in translating different languages, it may be best to bring up the problem at interwiki conflicts. If you find items where the language links appear to be inconsistent it is also a good idea to bring it up at interwiki conflicts.
Select recipient item
Once it has been determined that the items should be merged, one item is selected to be the recipient of the sitelinks and properties. This is usually the item that is used more often (possible indicators are links to the items or the number of sitelinks and statements it has). If you can't tell, best choose the one with the lowest Q####, as it is the oldest item.
Sitelinks can be moved manually from one item to another by first removing the link from the obsolete item, and then adding it to the recipient item. If you try to add the sitelink to the recipient item before removing it from the obsolete item there will be a conflict. There is a gadget in your preferences called "Move" that gives users the ability to move sitelinks quickly. Once the gadget is enabled, go to the obsolete item, select the link you wish to move, click "move", then input the Q#### of the recipient item.
Move label and description
Correct labels, descriptions and aliases that are present in the obsolete item, but not present in the recipient item, should simply be added to the recipient item. If a different label is already present, you can add the label of the obsolete item as an alias. To check which labels, descriptions and aliases are present in various languages, it is advisable to turn on the labelLister gadget in your preferences.
The autoEdit gadget can in some cases be used to generate new labels and descriptions for the recipient item, which may be easier than to move them from the obsolete them.
Correct properties that are present in the obsolete item, but not present in the recipient item, should simply be added to the recipient item. Be sure not to add properties that are already present.
Check with What links here to see if any other items link to the obsolete item. If that is the case, go to each of these items and change the value of properties which have the obsolete item as value to the recipient item.
Once all the sitelinks, properties, labels, and descriptions have been moved and copied to the recipient item, the obsolete item can then be deleted. To do this, put in a request at RfD and state "Merged into [[Q####]]" (replace "Q####" with the recipient item). There is a gadget in your preferences called "RequestDeletion" that gives users the ability to request deletion quickly.
If you have any questions about merging items, feel free to ask them on this page's talk page.
Where can I find items to merge?
Now that you know how to merge, you can make use of your new skill at various places on Wikidata where potential duplicates are found/listed. These places include:
- Bene's tool and Sanyi's tool
- tools that can be used to find items containing only one interwiki link
- page hosts many lists of merge candidates (not updated since August 2013)
- species and astronomy potential merges (not updated since November 2013)
- search tool to find articles that are not yet linked to other Wikipedias/Wikivoyages (a more specific tool: Not in the other language lists articles in a category in Wikipedia A not linked with Wikipedia B)
- Constraint violations
- sometimes certain constraint violations may indicate a duplication, particularly "Unique value" violations
Feel free to add any more useful pages!