"beer(at)cmu(dot)edu" <beer(at)cmu(dot)edu> writes:
> lo_creat fails with:
>      ERROR: large object <oid> already exists
Well, does it?
What PG version is this?  I'm suspicious that it's pre-8.1 and the
problem is that your OID counter has wrapped around to a region that
is already pretty densely populated with large objects.  8.1 and up
are able to pick unused OIDs but earlier versions just fail on
collisions.
			regards, tom lane