Well the problem is occurring again, but this time it is intermittent. I think the crux of the issue is that Linux isn't giving swap to Postgres - and possibly other - processes. Why this is the case I do not know and will research. I may shrink work_mem or add more RAM, but I'd rather use swap rather than completely blow up for those times when the cup runneth over just a bit. I'll post the resolution to the issue if I find it... Mark
