Re work_mem: I think this is per query and thus might affect every connection?! At least thats what I gather from 'PostgreSQL 9.0 High Performance' Re temp_buffers: 'Sets the maximum number of temporary buffers used by each database session.' For us it practically means per connection. Not for you?
Shit, I'm missing the version! 9.3. I edited the blog post.
Re memory: I think that really depends on the application I think. We have many idle connections.
It means that potentially every connection may at some point use this amount of memory, but idle connections will not. If you have 20 busy connections and 350 idle ones, at most 20 x temp_buffers will be used and there is no benefit from PGbouncer in this regard. If you have 370 busy connections, all of them might use temp_buffers and your tradeoff can be 370 concurrently executing queries at higher memory cost vs. e.g. 20 concurrently executing queries via PGbouncer at lower memory cost and 350 stalled queries with potentially high latency.
> We have many idle connections.
In this case, you will not have any issues with memory use from temp_buffers, work_mem ...
I was trying to gather everything relevant to resources per connection. I'm not saying work_mem caused our problem.