Re: 12c pluggable database shared SGA question
Date: Thu, 18 Sep 2014 13:33:31 +1000
Message-ID: <CALn1tDsyRgGxhcU=Jkps9Lf6JJT4qJgq-3jem00e2VqW+v7Rww_at_mail.gmail.com>
I think we also need to factor the bloat in the data dictionary when you consolidate so many databases in this multitenant world. At a previous workplace we were trialling a 12c multitenant environment and I tried a few scalability tests.
I documented some of my findings here :
http://www.stojanveselinovski.com/blog/2014/03/03/too-many-pdbs-part-2/ but
unfortunately I wasn't able to finish it off as I moved to greener pastures.
What I found interesting is managing these pdbs with DB control was chewing up to 50% of the available cpu at times with parallel queries over the CDB_ views. There was no load on the system other than db control. Again, there wasn't much science to these tests and time constraints prevented any further analysis.
Once management were aware of the costs of this PDB thing it got shut down pretty quickly. Just can't see many use cases for multitenancy at this price point.
Stojan
www.stojanveselinovski.com/blog
www.stojanveselinovski.com
On Wed, Sep 17, 2014 at 2:57 PM, Connor McDonald <mcdonald.connor_at_gmail.com> wrote:
> Regarding "I am, however, skeptical that there is any problem getting
> enough DRAM bolted to modern CPUs"
>
> This is true, but there (sadly) is large difference between what the
> hardware is capable of, what the incredible cheap cost is.... versus some
> infrastructure manager stuck in the 90's quibbling over an extra 16G to
> bring the server up to a "ridiculous" 48G....
>
> sigh....
>
> I know some clients who are "excited" at multitenant as a way of reducing
> their total SGA and they remain excited no matter how many times you tell
> them just to head down the local IT shop and ffs just buy more RAM.....
>
>
>
>>
>
> --
> Connor McDonald
> ===========================
> blog: connormcdonald.wordpress.com
> web: http://www.oracledba.co.uk
>
> "If you are not living on the edge, you are taking up too much room."
> - Jayne Howard
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Thu Sep 18 2014 - 05:33:31 CEST