PostgreSQL: sweet spot for core count

Question

I have a few questions re. PostgreSQL.

1. What is the sweet spot so far as number of CPU cores goes?
2. Does anyone know when parallel queries will be implemented?
3. WRT #2, I've seen benchmarks where PostgreSQL beats SQL Server. What is the real implications of not having parallel queries?

Thanks.

Answer 1

1. If you have a lot of contention, there is some anecdotal evidence that performance doesn't get better or degrades after about 32 CPU cores. It is difficult to get definitive results in that area, though. If someone knew the answer, they would probably also be able to fix the problem. If you think your application will be pushing the limits on this, I suggest running tests yourself. pgbench might help you get started.

2. It doesn't look as though it will happen anytime soon. Don't plan on it.

3. This is highly dependent on what you are doing. If you have an OLTP application with lots of concurrent clients, it won't matter much. If you have more of an OLAP style usage, then it will suck because you might only be using one or two out of many CPUs, and especially your sorts could conceivably be faster.