As a rather blanket answer: Yes it is, why shouldn't it be?
For a real answer, please provide some context information: Which Mageia version are you using, and why do you want to upgrade?
For Mageia 2, there will be no major KDE upgrade anymore as there was already an upgrade from 4.8.2 to 4.8.5, maybe only a similar minor upgrade.
If you really want to use KDE 4.9, you can try Cauldron, the Mageia development version:
https://wiki.mageia.org/en/CauldronBut please read the warnings on above linked wiki page.