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From Jake Luciani <jak...@gmail.com>
Subject Re: Second Cassandra users survey
Date Wed, 09 Nov 2011 10:53:20 GMT
Hi Todd,

Entity Groups : https://issues.apache.org/jira/browse/CASSANDRA-1684

-Jake

On Wed, Nov 9, 2011 at 6:44 AM, Todd Burruss <bburruss@expedia.com> wrote:

> I believe I heard someone talk at Cassandra SF conference about creating a
> partitioner that was a derivation of RandomPartitioner.  It essentially
> would look for keys that adhere to a certain pattern, like <key>:<subkey>.
>  The <key> portion would be used for determining the location on the ring,
> but <key>:<subkey> for actually storing.  This would allow groups of data
> (all having the same <key>) to reside on the same node, while still
> maintaining uniqueness across the entire keyspace.
>
> Unbalanced nodes could still occur, but I don't think any worse than
> wide/large rows can cause.
>
>
> On 11/8/11 1:29 AM, "Daniel Doubleday" <daniel.doubleday@gmx.net> wrote:
>
> >Ah cool - thanks for the pointer!
> >
> >On Nov 7, 2011, at 5:25 PM, Ed Anuff wrote:
> >
> >> This is basically what entity groups are about -
> >> https://issues.apache.org/jira/browse/CASSANDRA-1684
> >>
> >> On Mon, Nov 7, 2011 at 5:26 AM, Peter Lin <woolfel@gmail.com> wrote:
> >>> This feature interests me, so I thought I'd add some comments.
> >>>
> >>> Having used partition features in existing databases like DB2, Oracle
> >>> and manual partitioning, one of the biggest challenges is keeping the
> >>> partitions balanced. What I've seen with manual partitioning is that
> >>> often the partitions get unbalanced. Usually the developers take a
> >>> best guess and hope it ends up balanced.
> >>>
> >>> Some of the approaches I've used in the past were zip code, area code,
> >>> state and some kind of hash.
> >>>
> >>> So my question related deterministic sharding is this, "what rebalance
> >>> feature(s) would be useful or needed once the partitions get
> >>> unbalanced?"
> >>>
> >>> Without a decent plan for rebalancing, it often ends up being a very
> >>> painful problem to solve in production. Back when I worked mobile
> >>> apps, we saw issues with how OpenWave WAP servers partitioned the
> >>> accounts. The early versions randomly assigned a phone to a server
> >>> when it is provisioned the first time. Once the phone was associated
> >>> to that server, it was stuck on that server. If the load on that
> >>> server was heavier than the others, the only choice was to "scale up"
> >>> the hardware.
> >>>
> >>> My understanding of Cassandra's current sharding is consistent and
> >>> random. Does the new feature sit some where in-between? Are you
> >>> thinking of a pluggable API so that you can provide your own hash
> >>> algorithm for cassandra to use?
> >>>
> >>>
> >>>
> >>> On Mon, Nov 7, 2011 at 7:54 AM, Daniel Doubleday
> >>> <daniel.doubleday@gmx.net> wrote:
> >>>> Allow for deterministic / manual sharding of rows.
> >>>>
> >>>> Right now it seems that there is no way to force rows with different
> >>>>row keys will be stored on the same nodes in the ring.
> >>>> This is our number one reason why we get data inconsistencies when
> >>>>nodes fail.
> >>>>
> >>>> Sometimes a logical transaction requires writing rows with different
> >>>>row keys. If we could use something like this:
> >>>>
> >>>> prefix.uniquekey and let the partitioner use only the prefix the
> >>>>probability that only part of the transaction would be written could
> >>>>be reduced considerably.
> >>>>
> >>>>
> >>>>
> >>>> On Nov 1, 2011, at 11:59 PM, Jonathan Ellis wrote:
> >>>>
> >>>>> Hi all,
> >>>>>
> >>>>> Two years ago I asked for Cassandra use cases and feature requests.
> >>>>> [1]  The results [2] have been extremely useful in setting and
> >>>>> prioritizing goals for Cassandra development.  But with the release
> >>>>>of
> >>>>> 1.0 we've accomplished basically everything from our original wish
> >>>>> list. [3]
> >>>>>
> >>>>> I'd love to hear from modern Cassandra users again, especially if
> >>>>> you're usually a quiet lurker.  What does Cassandra do well?  What
> >>>>>are
> >>>>> your pain points?  What's your feature wish list?
> >>>>>
> >>>>> As before, if you're in stealth mode or don't want to say anything
in
> >>>>> public, feel free to reply to me privately and I will keep it off
the
> >>>>> record.
> >>>>>
> >>>>> [1]
> >>>>>
> http://www.mail-archive.com/cassandra-dev@incubator.apache.org/msg0114
> >>>>>8.html
> >>>>> [2]
> >>>>>
> http://www.mail-archive.com/cassandra-user@incubator.apache.org/msg014
> >>>>>46.html
> >>>>> [3]
> >>>>>http://www.mail-archive.com/dev@cassandra.apache.org/msg01524.html
> >>>>>
> >>>>> --
> >>>>> Jonathan Ellis
> >>>>> Project Chair, Apache Cassandra
> >>>>> co-founder of DataStax, the source for professional Cassandra support
> >>>>> http://www.datastax.com
> >>>>
> >>>>
> >>>
> >
>
>


-- 
http://twitter.com/tjake

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