Yes.64-bit.
The UltraSPARC-II cpu modules are native 64-bit architecture.
Solaris 7 and newer would install a 64-bit kernel on that platform by default.
Solaris 8 and newer do not have 32-bit-only kernels,
but have a 32-bit compatibility innate to them, that they can run
well behaved 32-bit applications in their 64-bit environments.
Match your version of your database software to the
appropriate version of Solaris.
E450 in the Sun System Handbook:
http://sunsolve.sun.com/handbook_pub/Systems/E450/E450.html
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Edit:
You can find many items of information on this topic
with a quick Google search, keyword ultrasparc-ii.
For example, there's this Sun press release from November 1998:
http://www.sun.com/smi/Press/sunflash/1998-11/sunflash.981102.2.xml