On 26.06.2013 18:34, Kevin Grittner wrote:
Markus Wanner<mar...@bluegap.ch> wrote:
On 06/25/2013 11:52 PM, Kevin Grittner wrote:
At least until we have parallel
query execution. At *that* point this all changes.
Can you elaborate on that, please? I currently have a hard time
imagining how partitions can help performance in that case,
either.
Well, partitioning will *still* be a net loss for overall
throughput on a machine with enough active connections to keep all
the resources busy. Where it will help is when you have a machine
with a lot of cores and a few big "reporting" style queries. Since
we currently can only use one core for a single query, we leave a
lot of CPU time (often the bottleneck for such queries) unused. If
we allow a large query to search multiple partitions in parallel, a
big query can complete sooner.
We could also allow a large query to search a single table in parallel.
A seqscan would be easy to divide into N equally-sized parts that can be
scanned in parallel. It's more difficult for index scans, but even then
it might be possible at least in some limited cases.
- Heikki
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
