Why is the ##UserID## parameter not populated in Data Explorer anymore?

Question

Environment

I'm logging in using the OpenID from http://openid.stackexchange.com and using Chrome 31.0.1650.57 m if that matters.

Steps to reproduce:

Log in to Data Explorer and compose a query, for example, like:

DECLARE @MyUserID INT = ##UserID:int##

SELECT TOP 1
    Id AS [Post Link],
    Score AS [Score],
    CreationDate AS [Creation Date]
FROM
    Posts
WHERE
    OwnerUserId = @MyUserID AND
    PostTypeId IN (2, 3)
ORDER BY
    CreationDate
DESC

Then press the Run Query button and see if the UserID field is filled with your own user ID like shown in the below screenshot:

Question:

Did something changed on the ##UserID## parameter (for example, that it's not supported anymore)?

• If so, then there is an outdated help paragraph about it (What's the point of logging in).
• If not, it is a bug which is there about three days (I've been waiting since I noticed that you were going to do some changes to Data Explorer, but it remains there, hence my question).

Answer 1

OK, I cracked it.

The bottom line is it's because Stack Exchange changed the Gravatar hashing algorithm recently, see here:

A fairly recent article on ArsTachnica, regarding how using Gravatars can leak an email address has prompted us to make some changes to how we produce the gravatar hash (under certain circumstances).

And the code to find the UserID per site is: (source)

string hash = Util.GravatarHash(user.Email);
try
{
    return cnn.Query<int?>("select top 1 Id from Users where EmailHash = @hash order by Reputation desc", new {hash}).FirstOrDefault();
}
catch
{
    // Allow this to fail, its not critical
}

Which means Data Explorer is looking for hash that was changed. It didn't affect all users (see "under certain circumstances" in Oded's reply).

Note: at some point after writing this answer, SE removed the hash from the database and blanked out all existing Gravatar hashes, i.e. the value of EmailHash in Users table is always null now. This means there's no way to get the user id parameter auto populated any longer.

Answer 2

I've written a small userscript, SEDE User ID Autofiller, to restore this functionality for users (like me) where the standard functionality doesn't work. As a bonus, it will autofill ##AccountId## parameters with your network account ID for cross-site queries.