Hi,
2011/11/8 Craig Ringer <ringerc@ringerc.id.au>:
> "Spreads reads too much" ?
>
> Are you saying there's too much random I/O? Is it possible it'd benefit from
> a column store?
> When you're using Greenplum are you using "Polymorphic Data Storage" column
> storage "WITH (orientation=column)" ?
yes, exactly. Column store and compression speed up queries even more
(sometimes beyond 100x times) comparing to postgres.
>
> Or is the performance different just in better utilisation of the hardware
> under Greenplum?
>>
Yes, looks like that they can better utilise available hardware.
>> Is there
>> a way to get PG backed IO stats using stock CentOS (5.7) kernel and
>> tools? (I can't change my env easily)
>
> Dunno; check postgresql high performance (book), the manual, etc. Useful
> tools are the pg_stat_ tables, "vmstat", "iostat", "iotop", etc.
Yeah, I know about those.. I like iotop but enterprise distributions
do not ship fresh kernels... I need something which can I "safely"
(slightly worse performance is acceptable but machine must survie) run
in production for several hours and then cross reference it with
postgres and other system logs
> That said, Pg's codebase isn't exactly trivial :S and trying to get involved
> in major re-engineering like parallelisation isn't going to be practical
> when you're just getting started.
That's what I meant ;)
--
Ondrej Ivanic
(ondrej.ivanic@gmail.com)
