On Wed, 2008-09-10 at 00:02 -0600, Scott Marlowe wrote: > Unless you have either a small data set or a very powerful RAID array, > most the time you won't be CPU bound anyway. But it would be nice to > see some work come out to parallelize some of the work done in the > back end.
I would have agreed with this several years ago, but many folks now buy enough RAM to reduce the impact of IO. We're routinely CPU-bound on small queries, and even on some large ones, on a 32GB / 16-core Opteron box that serves a ~200GB database (on disk tables+indexes). Does anyone know of research/references on query optimizers that include parallelization as part of the cost estimate? I can envision how PostgreSQL might parallelize a query plan that was optimized with an assumption of one core. However, I wonder whether cpu and io costs are sufficient for efficient parallel query optimization -- presumably contention for memory (for parallel sorts, say) becomes critical. -Reece -- Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0
