(In reply to comment #0)

The field has been populated retroactively on enwiki, but not on other wikis.

No, I don't believe so. See, for example, http://en.wikipedia.org/w/api.php?action=query&list=users&ususers=Dobriain|Versageek&usprop=registration

This sounds like a direct duplicate of bug 18638.

• This bug has been marked as a duplicate of bug 18638 ***

(In reply to MZMcBride from comment #1)

(In reply to comment #0)

The field has been populated retroactively on enwiki, but not on other wikis.

No, I don't believe so.

Probably only partially. Pathoschild's stalktoy very clearly displays that for some users there is precise registration date on en.wiki even before 2005, when there wasn't any. Should be trivial to verify.

Bug 18638 is not really a duplicate unless the script runs itself on its own, better separate the two issues even though this is blocked by that one (-shell because this is not actionable yet).

(In reply to Nemo from comment #3)

Probably only partially. Pathoschild's stalktoy very clearly displays that
for some users there is precise registration date on en.wiki even before
2005, when there wasn't any. Should be trivial to verify.

To clarify: when the fixUserRegistration.php maintenance script is run, it can only change NULL user.user_registration values to a non-NULL value if there is an existent edit for the associated account when the script is run. For many old users (user accounts created prior to 2005 especially), a NULL user.user_registration value or even an inaccurate value is somewhat expected.

While I thought that fixUserRegistration.php had been run on all Wikimedia wikis, [[wikitech:Server admin log/Archive 7#June 5]] indicates that it may have only been run on the English Wikipedia.

In T24097#263825, @MZMcBride wrote:

While I thought that fixUserRegistration.php had been run on all Wikimedia wikis, [[wikitech:Server admin log/Archive 7#June 5]] indicates that it may have only been run on the English Wikipedia.

Surely not fixed for commons: https://commons.wikimedia.org/w/api.php?action=query&list=users&format=xml&usprop=registration&ususers=Planemad|McZusatz

If we must put some value in that field, can we at least do something better like choosing a timestamp between [date for previous user_id, date for next user_id] where those values can be existing values or values based on first edit, or values from the now deleted wikipages where these were logged in early MedaWiki.

In T24097#1124737, @Nikerabbit wrote:

If we must put some value in that field, can we at least do something better like choosing a timestamp between [date for previous user_id, date for next user_id] where those values can be existing values or values based on first edit, or values from the now deleted wikipages where these were logged in early MedaWiki.

+1. There are some more suggestions in T20638