Any way to use >1 Core in PostgreSQL for a single Connection/Query?

Question

I get that Postgres scales automatically to multicore with multiple connections, but what about when I'm running a massive query on a SINGLE connection? So frustrating that the CPU usage maxes out at 25% on my 4-core system.

I'm in process of switching from SQL Server and this is the only thing so far that really bugs me. SQL Server will use up to 100% of my CPU for a single connection/query.

I'm running 9.2 on Windows 7 Enterprise 64-bit with Xeon processor if it matters.

If there is not way to get around this, could someone address why this isn't seen as an issue? Is it because Postgres is focused on multi-user scenarios?

Answer 1

PostgreSQL does not currently support executing a single query across multiple CPU cores (minus background things like background writing and wal writing if you're doing a write query, but that doesn't really count). It's work that's in progress, but it's a long-term project, and is not in any current version of PostgreSQL.

This is the same on all platforms and architectures.

It is definitely an issue, but since PostgreSQL is, as you say, focused on multi user scenarios, it's not bubbled to the top of the priority queue until recently. But there are definitely people realizing it's an issue, and working on solving it for future versions, it's just not done yet.

Answer 2

There is a Foreign Data Wrapper that aims to add parallelism via the GPU called pg_strom. I've never used it, and it looks quite specialized, but maybe you (or someone here) has a use-case for it.

Article describing pg_strom

http://gpuscience.com/software/postgresql-gpu-pgstrom/

The code:

https://github.com/kaigai/pg_strom

Answer 3

It's not that it isn't seen as a problem. It's that it requires fundamental architectural changes. The use case for it is pretty specialised. It would only help on data warehouse type environments where you're executing long queries one at a time -- AND the queries are CPU bound, not disk i/o bound as they would usually be.