Peter Geoghegan wrote: > On 29 November 2011 15:31, Bruce Momjian <br...@momjian.us> wrote: > > These are exciting advanced you are producing and I am hopeful we can > > get this included in Postgres 9.2. > > Thanks Bruce. > > >I have mentioned already that I > > think parallelism is the next big Postgres challenge, and of course, one > > of the first areas for parallelism is sorting. > > I'm not sure that sorting has that much to recommend it as an initial > target of some new backend parallelism other than being easy to > implement. I've observed the qsort_arg specialisations in this patch > out-perform stock qsort_arg by as much as almost 3 times. However, the > largest decrease in a query's time that I've observed was 45%, and > that was for a contrived worst-case for quicksort, but about 25% is > much more typical of queries similar to the ones I've shown, for more > normative data distributions. While that's a respectable gain, it > isn't a paradigm shifting one, and it makes parallelising qsort itself > for further improvements quite a lot less attractive - there's too > many other sources of overhead.
Agreed. I think your improvements make it likely we will address not address sort parallelism first. With all the improvements coming in Postgres 9.2, we might need to look at I/O parallelism first. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers