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From Robin Verlangen <ro...@us2.nl>
Subject Re: 1000's of column families
Date Fri, 28 Sep 2012 11:19:11 GMT
I think I misunderstood your "all data in one location" note. I thought you
meant to store it all in one CF.

Best regards,

Robin Verlangen
*Software engineer*
*
*
W http://www.robinverlangen.nl
E robin@us2.nl

<http://goo.gl/Lt7BC>

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2012/9/28 Hiller, Dean <Dean.Hiller@nrel.gov>

> I thought someone was saying each column family added to RAM on every node
> not RAM on a single node.  It adds RAM on every node???  So eventually, I
> will run out?  Was that person wrong?  This would mean adding nodes does
> not help if he is right.  Can anyone confirm this?
>
> Thanks,
> Dean
>
> From: Robin Verlangen <robin@us2.nl<mailto:robin@us2.nl>>
> Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <
> user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> Date: Thursday, September 27, 2012 11:52 PM
> To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <
> user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> Subject: Re: 1000's of column families
>
> "so if you add up all the applications
> which would be huge and then all the tables which is large, it just keeps
> growing.  It is a very nice concept(all data in one location), though we
> will see how implementing it goes."
>
> This shouldn't be a real problem for Cassandra. Just add more nodes and
> ever node contains a smaller piece of the cake (~ring).
>
> Best regards,
>
> Robin Verlangen
> Software engineer
>
> W http://www.robinverlangen.nl
> E robin@us2.nl<mailto:robin@us2.nl>
>
> [http://static.cloudpelican.com/images/CloudPelican-email-signature.jpg]<
> http://goo.gl/Lt7BC>
>
> Disclaimer: The information contained in this message and attachments is
> intended solely for the attention and use of the named addressee and may be
> confidential. If you are not the intended recipient, you are reminded that
> the information remains the property of the sender. You must not use,
> disclose, distribute, copy, print or rely on this e-mail. If you have
> received this message in error, please contact the sender immediately and
> irrevocably delete this message and any copies.
>
>
>
> 2012/9/27 Hiller, Dean <Dean.Hiller@nrel.gov<mailto:Dean.Hiller@nrel.gov>>
> Unfortunately, the security aspect is very strict.  Some make their data
> public but there are many projects where due to client contracts, they
> cannot make their data public within our company(ie. Other groups in our
> company are not allowed to see the data).
>
> Also, currently, we have researchers upload their own datasets as well.
> Ideally, they want to see this one noSQL store as the place where all data
> for the company livesÅ ALL of it so if you add up all the applications
> which would be huge and then all the tables which is large, it just keeps
> growing.  It is a very nice concept(all data in one location), though we
> will see how implementing it goes.
>
> How much overhead per column family in RAM?  So far we have around 4000
> Cfs with no issue that I see yet.
>
> Dean
>
> On 9/27/12 11:10 AM, "Aaron Turner" <synfinatic@gmail.com<mailto:
> synfinatic@gmail.com>> wrote:
>
> >On Thu, Sep 27, 2012 at 3:11 PM, Hiller, Dean <Dean.Hiller@nrel.gov
> <mailto:Dean.Hiller@nrel.gov>>
> >wrote:
> >> We have 1000's of different building devices and we stream data from
> >>these devices.  The format and data from each one varies so one device
> >>has temperature at timeX with some other variables, another device has
> >>CO2 percentage and other variables.  Every device is unique and streams
> >>it's own data.  We dynamically discover devices and register them.
> >>Basically, one CF or table per thing really makes sense in this
> >>environment.  While we could try to find out which devices "are"
> >>similar, this would really be a pain and some devices add some new
> >>variable into the equation.  NOT only that but researchers can register
> >>new datasets and upload them as well and each dataset they have they do
> >>NOT want to share with other researches necessarily so we have security
> >>groups and each CF belongs to security groups.  We dynamically create
> >>CF's on the fly as people register new datasets.
> >>
> >> On top of that, when the data sets get too large, we probably want to
> >>partition a single CF into time partitions.  We could create one CF and
> >>put all the data and have a partition per device, but then a time
> >>partition will contain "multiple" devices of data meaning we need to
> >>shrink our time partition size where if we have CF per device, the time
> >>partition can be larger as it is only for that one device.
> >>
> >> THEN, on top of that, we have a meta CF for these devices so some
> >>people want to query for streams that match criteria AND which returns a
> >>CF name and they query that CF name so we almost need a query with
> >>variables like select cfName from Meta where x = y and then select *
> >>from cfName where xxxxx. Which we can do today.
> >
> >How strict are your security requirements?  If it wasn't for that,
> >you'd be much better off storing data on a per-statistic basis then
> >per-device.  Hell, you could store everything in a single CF by using
> >a composite row key:
> >
> ><devicename>|<stat type>|<instance>
> >
> >But yeah, there isn't a hard limit for the number of CF's, but there
> >is overhead associated with each one and so I wouldn't consider your
> >design as scalable.  Generally speaking, hundreds are ok, but
> >thousands is pushing it.
> >
> >
> >
> >--
> >Aaron Turner
> >http://synfin.net/         Twitter: @synfinatic
> >http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
> >Windows
> >Those who would give up essential Liberty, to purchase a little temporary
> >Safety, deserve neither Liberty nor Safety.
> >    -- Benjamin Franklin
> >"carpe diem quam minimum credula postero"
>
>
>

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