prstat defines SWAP as:
The sum of swap reservations of the associated processes
for each user, project, task, or zone. This counts
shared memory only once for each user, project, task, or
zone. Swap is reserved when anonymous memory is allo-
cated or files are mapped private. The value of swap is
expressed in kilobytes (K), megabytes (M), or gigabytes
(from prstat(1M) on Solaris 10, cf. Open Solaris prstat)
Basically this means that the value includes memory that is currently not accessed yet but is mapped into the address space of a process. Such memory may be used in the future, and thus may be swapped out (i.e. written to a swap partition for real). Thus on creating the initial mapping Solaris prstat counts them as SWAP.
This does not mean that this amount of memory is actually written to the SWAP partition or is necessarily going to be written to it.
Those swap reservations, anonymous memory and mapped files are part of the virtual memory system of Solaris.
Also note that you are using
-t - thus the shown value in your example is not the one of an oracle process but the aggregate value of all processes running under user
Using some Solaris port of
top provides more useful information, i.e. a SIZE (or VMEM) and a RES (or RSS) value. VMEM includes all virtual memory pages and RSS is the resident size. With that the relation VMEM >= RSS is true (for prstat RSS may be > SWAP, i.e. RSS is not included in SWAP).
If you are concerned with actual swap activity you can use something like