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From Ravikumar Govindarajan <ravikumar.govindara...@gmail.com>
Subject Re: Key-Token mapping in cassandra
Date Fri, 19 Apr 2013 16:57:27 GMT
I think I have simplified my example a little too much.

Lets assume that there are groups and users.

Ideally a grpId becomes the key and it holds some meta-data.

Lets say GroupMetaCF

grpId --> key, entityId --> col-name, blobdata --> col-value

Now we have a UserTimeSeriesCF

grpId/userId --> key, UUID --> col-name, entityId --> col-value

[Each user will view a subset of the grp data, based on roles etc...]

There are many more such CFs all with prefixes of "grpId". By hashing grpId
to cassandra's token, I thought we can co-locate all the group's data into
one set of replicated nodes.

Is there a way to achieve this?

--
Ravi


On Thu, Apr 18, 2013 at 1:26 PM, aaron morton <aaron@thelastpickle.com>wrote:

> All rows with the same key go on the same nodes. So if you use the same
> row key in different CF's they will be on the same nodes. i.e. have CF's
> called Image, Documents, Meta and store rows in all of them with the 123
> key.
>
> Cheers
>
> -----------------
> Aaron Morton
> Freelance Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 18/04/2013, at 1:32 PM, Ravikumar Govindarajan <
> ravikumar.govindarajan@gmail.com> wrote:
>
> Thanks Aaron.
>  We are looking at co-locating all keys for a given user in one Cassandra
> node.
> Are there any other ways to achieve this
>
> --
> Ravi
>
> On Thursday, April 18, 2013, aaron morton wrote:
>
>> CASSANDRA-1034
>>
>> That ticket is about removing an assumption which was not correct.
>>
>> I would like all keys with "123" as prefix to be mapped to a single token.
>>
>> Why?
>> it's not possible nor desirable IMHO. Tokens are used to identify a
>> single row internally.
>>
>> Cheers
>>
>>    -----------------
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 17/04/2013, at 11:25 PM, Ravikumar Govindarajan <
>> ravikumar.govindarajan@gmail.com> wrote:
>>
>> We would like to map multiple keys to a single token in cassandra. I
>> believe this should be possible now with CASSANDRA-1034
>>
>> Ex:
>>
>> Key1 --> 123/IMAGE
>> Key2 --> 123/DOCUMENTS
>> Key3 --> 123/MULTIMEDIA
>>
>> I would like all keys with "123" as prefix to be mapped to a single token.
>>
>> Is this possible? What should be the Partitioner that I should most
>> likely extend and write my own to achieve the desired result?
>>
>> --
>> Ravi
>>
>>
>>
>

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