We can improve the performance of system/custom reports by not requesting the same data multiple times, e.g. when two or more columns select the same table fields

Assume report contains 3 columns, which select fields as follows:

1. column1
   • id
   • name
   • colour
2. column2
   • name
   • altname
3. column3
   • id
   • location

We end up with something like the following

SELECT

    id AS c1_id, name AS c1_name, colour AS c1_colour,

    name AS c2_name, altname AS c2_altname,

    id AS c3_id, location AS c3_location

FROM ...

Report builder should optimise the query and remove the duplicate fields being selected (in this trivial case: id, name)