Merging page histories is done using Special:MergeHistory. This lets the user merge revisions of the history of one source page into a newer page. The user can use the radio button column to merge in only the revisions created at and before the specified time. Special:Logs/merge will then present the user with an "Unmerge" button to reverse the merge. This is done by switching the source and destination pages in Special:MergeHistory.
Merging pages works by changing the
rev_page field in the revision table.
When you merge two pages, the source page must generally be older than the destination page, because Special:MergeHistory will only allow revisions to be prepended to a page's history—mixing histories would not make sense.
When merging, the selected revisions from the source page will be set as revisions of the destination page.
logging.log_params holds the page title of the destination page and the timestamp.
A sample API:Logevents API result:
<item logid="6" ns="0" title="Foo" pageid="2" logpage="2" type="merge" action="merge" user="FooUser" timestamp="2014-09-16T17:43:05Z" comment=""> <param>Bar</param> <param>20140916174244</param> </item>