Automatically calculate data type

System: Cognos Analytics Reporting
Actor: User wanting to develop a report or explore data

Cognos Analytics Reporting is used to explore data and produce reports, both of which lead to making decisions.

Description:
When performing a calculation using a Query Calculation (like concatenating two character values), Cognos gets confused and writes some really bad SQL. It produces multiple subqueries that are joined directly and by matching NULL values. The join looks something like this:

WHERE
(T1.C1 = T2.C1 or (T1.C1 is null and T2.C1 is null)) and
(T1.C2 = T2.C2 or (T1.C2 is null and T2.C2 is null))

With a recent example involving half a dozen columns in the join, this makes what would otherwise be a 2 second query take over 2 minutes to run -- about 60 times as long as it should. This can create a tremendous load on the database server and is very inconvenient for the user.

My example is computing a field for the list that is Employee_First_Name - space - Employee_Last_Name, like "John Smith". The expression looks like this:
[Timesheet].[Employee].[EmployeeFirstName] + ' ' + [Timesheet].[Employee].[EmployeeLastName]
Both of the query items from the package are of data type varchar(20), so the returned values will always fit into a varchar(41) -- and Cognos be able to compute this easily, but it doesn't. This leads to Cognos assuming that the computed column is a measure, summarizing it in a total row at the bottom of the list, and writing some really bad SQL. (...and even if I delete the total row, the problem still occurs.)

It turns out the solution for an admin or advanced report author would look like this:
cast([Timesheet].[Employee].[EmployeeFirstName] + ' ' + [Timesheet].[Employee].[EmployeeLastName], varchar(45))
...but A CASUAL BUSINESS USER WANTING TO EXPLORE THE DATA SHOULDN'T NEED TO KNOW THAT.

Solution:
Please have Cognos compute the appropriate data type automatically and make a better decision regarding SQL generation.
Alternatively, Cognos shouldn't assume that any Query Calculation is a measure. Perhaps the user should be asked to specify that in the expression editor.