Re: Postgres or Greenplum

 On Tue, 7 Jun 2011 23:04:04 +0100, Simon Riggs wrote:
> On Tue, Jun 7, 2011 at 10:26 PM, Simon Windsor
> <simon.windsor@cornfield.me.uk> wrote:
>
>> I have been using Postgres for many years and have recently discover
>> Greenplum, which appears to be a heavily modify Postgres based,
>> multi node
>> DB that is VERY fast.
>>
>> All the tests that I have seen suggest that Greenplum when
>> implemented on a
>> single server, like Postgres, but with several  separate
>> installations can
>> be many time times faster than Postgres. This is achieved by using
>> multiple
>>  DBs to store the data and using multiple logger  and writer
>> processes to
>> fully use the all the resources of the server.
>>
>> Has the Postgres development team ever considered using this
>> technique to
>> split the data into separate sequential files that can be accessed
>> by
>> multiple writers/reader processes? If so, what was the conclusion?
>>
>> Finally,  thanks for all the good work over the years!
>
> Yes, I've looked at implementing parallel query a number of times. My
> estimate was that its about 2 man years effort to do something
> worthwhile there, and so far nobody has offered funding for such a
> task. There was some recent discussion about obtaining funding
> recently, so we'll see how that goes. It is of course reasonably
> straightforward to achieve trivial parallelism, but that's mostly
> useless in the real world. So its on the roadmap, but some way off
> yet.
>
> Many commercial implementations exist, and IMHO the Greenplum
> solution
> is the best general purpose DW solution currently available for
> PostgreSQL-like environments. Greenplum does have a community edition
> that is free to use and your stated performance results match my
> experience. We've worked with a number of data warehouse customers
> hitting the limits and moving up to Greenplum. Once people give up
> the
> Oracle mantra, it frees them to consider a range of alternatives.
>
> Main reasons for deferring work on parallel query has been that other
> techniques have been easier to achieve useful gains with. For
> example,
> partitioning allowed PostgreSQL to dramatically reduce scan times
> with
> less complexity. Synchronous scans can also achieve good efficiencies
> for cases where total throughput is important. I expect to do more
> work on improving decision support query performance in the next
> release (9.2), so if anybody wishes to partially fund development
> that
> would be much appreciated.
>
> --
>  Simon Riggs                   http://www.2ndQuadrant.com/
>  PostgreSQL Development, 24x7 Support, Training & Services

 But, I think GreenPlum is "share nothing", isn't it?

 Regards,
 Radek