Help:Merge

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A merge is performed when two or more items exist in Wikidata on the same topic, concept, or object. A merge is a multistep process, first requiring that the collective data about the items be pooled together in one page (the recipient item), and finally resulting in the redirection of the obsolete page to the recipient item.

A merge can be done either automatically or manually by moving sitelinks and statements into one item, and then redirecting the obsolete item(s). Automatic merges with the merge gadget are preferred.

This guide explains how to enable automatic merges by activating the Merge gadget in your preferences and a few secondary methods.

If you have any questions about merging items, feel free to ask them on the Project Chat.

Check to be sureEdit

Make sure that the items are indeed about the same topic, concept, or object. There could be subtle differences requiring the existence of two or more items.

ExamplesEdit

en:tree → de:Baum (German word for tree)
Merge?  Y
Reason: These are about the same thing (tree) and so should be merged into the (multilingual) item, tree (Q10884)
en:tree → de:Eiche (German word for oak tree)
Merge?  Y
Reason: These are different things (oak tree is a "subclass of" tree) and so should remain separate as two items; tree (Q10884) and oak (Q33036816), respectively
Miller (family name) → Miller (disambiguation page)
Merge?  Y
Reason: These are different concepts, even if some Wikipedia articles include family names on disambiguation pages. They should remain separate as two items; Miller (Q1605060) and Miller (Q304896), respectively


If you are unsure (for example, due to difficulty translating different languages), or come across items with sitelinks that appear to be inconsistent, it is best to bring up the problem at interwiki conflicts.

Automatic mergeEdit

 
Using the Merge gadget

There are two ways to perform an automatic merge: the Merge gadget or the Special "Merge two items" page.

Please bear in mind, that while automated merges will be terminated if an interwiki conflict is found, you should still always check that the items are the same since the tools simply perform merging that you select to be done. Special:MergeItems can resolve conflicts that are merely due to redirects.

GadgetEdit

Merge.js is a gadget by Ebrahim that helps moving sitelinks, labels, descriptions, aliases, and statements with references.

To enable this function, open Preferences, select Gadgets, check the box for Merge and hit the Save button. To use it, open either the recipient or obsolete item, go to the drop-down menu in the top bar (in the default skin, it is to the left of "Search"), select "Merge with...", and enter the ID of the other item into the merge wizard. Click on "Merge" when done.

Special:MergeItemsEdit

Special:MergeLexemesEdit

Special:MergeLexemes can be used to trigger a merge of two lexemes if (only if) the lemma, the language and the lexical category are identical. If one of them isn't identical, it may be that this can be corrected first.

Enter the L#### in the fields specifying which is the recipient lexeme ("The ID to merge to") and which is the obsolete lexeme ("The id to merge from").

QuickStatementsEdit

The QuickStatements 2 (Q29032512) tool, and its predecessor, QuickStatements (Q20084080) allow users to merge a series of items. See the instructions.

Mark as duplicateEdit

If two items can't be merged because of two different articles at a Wikipedia, these can be marked for merging with markasduplicate.js.[clarification needed]

The script also adds instance of (P31) = Wikimedia duplicated page (Q17362920) to the redundant item.

Manual merge: step by stepEdit

Items to be merged with sitelink conflictsEdit

If there is a sitelink conflict, items can't be merged as only one link per site is possible.

Until the two pages at the site (e.g. articles at English language Wikipedia) are merged, two items have to be kept at Wikidata.

  1. One of the two items should be marked with instance of (P31) Wikimedia duplicated page (Q17362920) and qualifier of (P642) the other (main) item. Usually the more recent item should be marked. Wikidata:Database reports/Identified duplicates lists all such items.
  2. Statements, other sitelinks and labels/descriptions can be moved from the redundant item to the main item.
  3. Once the articles at the site are merged, the two items can be merged and instance of (P31) Wikimedia duplicated page (Q17362920) deleted.

If the sitelink conflict is due to an article and a redirect pointing to the same article, the redirect can be removed and the items merged. Special:MergeItems even allows to merge them directly.

Finding items to mergeEdit

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:

Wikidata:The Game
Wikimedia tool which has gamified the merging process, offering candidate pages to potentially be merged by the user
User:Ivan A. Krestinin/To merge
lists of merge candidates based on similar page title strings
Projectmerge
lists of merge candidates based on sitelink names being identical
Commonsmerge and Uniquemerge
lists of merge candidates based on values of a property being same in two items
Bene's Lonely Items tool
finds items containing only one sitelink to a Wikimedia site (which therefore may need to be merged with other items linked to different Wikimedia language versions of the same page)
Not in the other language
lists items in a given category that are linked to articles in Wikipedia A but not in Wikipedia B
Constraint violations
summary of constraint violations for properties; in particular, "Unique value" violations may indicate a duplication
Wikidata:True duplicates
list of items having at least one sitelink which is due to a bug used in another item
Wikidata:Database reports/identical birth and death dates
based on date of birth (P569) and date of death (P570)
Wikidata:Database reports/Identified duplicates
items with Wikimedia duplicated page (Q17362920) waiting for Wikipedia to merge
Wikidata:VIAF/cluster/linking to multiple Wikidata items
items which, according to VIAF (see VIAF ID (P214)), are related to the same person - VIAF may sometimes be wrong

Other pages and projects in the Category:Merge candidates

Feel free to add any more useful pages or delete ones that are not actively updated!

UnmergingEdit

Canceling a wrong merge could be done in a few steps:

  1. Go to the history page of the item onto which the merge has been done and restore the revision just before the merge.
  2. Go to the history page of the merged item and restore the revision just before the merge.

The order is important (especially if the item has sitelinks) because articles can be linked to at most one item. So they should first be deleted on the item which got all the linked before they could be restored on the other one.

Some bots (KrBot for example) are known to replace the redirected items in statements with their target redirects a certain period of time (24 hours for KrBot) after the merge. The next step is to ping bot owners (like Ivan A. Krestinin) so they can run the code to cancel the if that period of time passed and some bot did the substitution, so that the statements can be restored with the right item. KrBot creates edit groups when fixing redirects, which may be reverted en masse using the EditGroups tool.

On a closely related topic, the help page Help:Split an item will help you if the item has not been merged but if statements on two topics are mixed-up on a unique item for some reason. It has guidelines on how to divide the statements on two items without re-entering the information by hand.

See alsoEdit

For related Help pages, see:

For additional information and guidance, see:

  • Project chat, for discussing all and any aspects of Wikidata
  • Wikidata:Glossary, the glossary of terms used in this and other Help pages
  • Help:FAQ, frequently asked questions asked and answered by the Wikidata community
  • Help:Contents, the Help portal featuring all the documentation available for Wikidata