Wikipedia:Selective deletion

The MediaWiki software allows administrators to remove individual revisions from the history of a page. Since the introduction of the RevisionDelete tool, it is used only for handling complex page history merges - see Administrators' guide/Fixing cut-and-paste moves.

Historical usage

 * This refers to the pre-RevisionDelete era.

Selective deletion is generally only done when the revisions contain personal information of a user or some other person (telephone numbers, etc.) or copyright violations. For most kinds of simple vandalism, merely reverting the page to a good version is considered sufficient.

Since deleting a revision effectively hides all traces of the edit ever being made, including the name of the editor who made it, doing so may violate the attribution requirement of the GFDL and CC BY-SA — not to mention making the article history potentially misleading — if the deleted revision introduces any changes that are maintained in the following non-deleted revisions. Thus, selective deletion should be used very sparingly, and should not be used in cases where legitimate edits have been made between the time the unwanted content was added and the time when it was subsequently found and removed. In problematic cases, contacting a developer with direct database access may be necessary to sort out the history.

Deleted revisions are available to administrators only. In order to further restrict the visibility of revision, a request for oversight can be filed.

Methods
Prior to the introduction of RevisionDelete, MediaWiki provided no way for administrators to directly delete only selected revisions; the only way to accomplish this was to first delete the entire article and then to restore the revisions one does not want to see deleted. This basic procedure alone is sufficient for simple cases, but it does have some problems if the article has a long history:


 * Restoring a large number, but not all, of the revisions requires selecting lots of checkboxes on the undelete form; this may be difficult in some browsers. (In Firefox, and perhaps some other browsers, a range of checkboxes may be selected by first clicking the box at one end of the range and then holding down the Shift key while clicking the box at the other end; for other browsers a JavaScript workaround may be useful.)
 * If the article already has some deleted revisions (because some had been selectively deleted before, for example), deleting it causes the previously deleted revisions to be mixed with the newly deleted ones; sorting them out again may be next to impossible. Thus, there is a risk that previously deleted versions containing unwanted  information may be accidentally restored when a later selective deletion is performed.

To avoid these problems, one of the following methods were used. The first method is somewhat simpler, but requires selecting lots of checkboxes. The second avoids this, at the cost of some extra steps especially if there are previously deleted revisions.

A

 * 1) Move the page to a new title (say, PageName/deleted revisions YYYY-MM-DD, where YYYY-MM-DD is today's date).
 * 2) If the original page had any previously deleted revisions, restore them, move them to a different title (say, PageName/old deleted revisions) and delete them again.
 * 3) Delete the page you moved in step 1.
 * 4) Restore all the revisions except the ones you want deleted.
 * 5) Move the restored revisions back to the original title.

B

 * 1) Check if the page has any previously deleted revisions.  If so:
 * 2) Move the page to a temporary title (say, PageName/temp).
 * 3) Restore the deleted revisions, move them away (say, to PageName/old deleted revisions) and delete them again.
 * 4) Move the page back to its original title.
 * 5) Delete the page.
 * 6) Restore only the revisions you want deleted.
 * 7) Move the page to a new title (say, PageName/deleted revisions YYYY-MM-DD, where YYYY-MM-DD is today's date) and delete them.
 * 8) Restore the remaining versions of the article.

Another difference between these methods is that the former leaves an entry in the page history marking the page moves, while in the latter the only trace of the process is left in the deletion/move logs. Depending on the circumstances, having the moves shown in the history may or may not be desirable, but generally it shouldn't make much difference.