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Date: Sat, 4 Feb 2012 18:24:14 -0500
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Subject: Re: yet a couple more questions on composite columns
From: Jim Ancona <jim@anconafamily.com>
To: user@cassandra.apache.org
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I've used "special" values which still comply with the Composite
schema for the metadata columns, e.g. a column of
1970-01-01:{accountId} for a metadata column where the Composite is
DateType:UTF8Type.

Jim

On Sat, Feb 4, 2012 at 2:13 PM, Yiming Sun <yiming.sun@gmail.com> wrote:
> Thanks Andrey and Chris. =A0It sounds like we don't necessarily have to u=
se
> composite columns. =A0From what I understand about dynamic CF, each row m=
ay
> have completely different data from other rows; =A0but in our case, the d=
ata
> in each row is similar to other rows; my concern was more about the
> homogeneity of the data between columns.
>
> In our original supercolumn-based schema, one special supercolumn is call=
ed
> "metadata" which contains a number of subcolumns to hold metadata describ=
ing
> each collection (e.g. number of documents, etc.), then the rest of the
> supercolumns in the same row are all IDs of documents belong to the
> collection, and for each document supercolumn, the subcolumns contain the
> document content as well as metadata on individual document (e.g. checksu=
m
> of each document).
>
> To move away from the supercolumn schema, I could either create two CFs, =
one
> to hold metadata, the other document content; or I could create just one =
CF
> mixing metadata and doc content in the same row, and using composite colu=
mn
> names to identify if the particular column is metadata or a document. =A0=
I am
> just wondering if you have any inputs on the pros and cons of each schema=
.
>
> -- Y.
>
>
> On Fri, Feb 3, 2012 at 10:27 PM, Chris Gerken <chrisgerken@mindspring.com=
>
> wrote:
>>
>>
>>
>>
>> On 4 February 2012 06:21, Yiming Sun <yiming.sun@gmail.com> wrote:
>>>
>>> I cannot have one composite column name with 3 components while another
>>> with 4 components?
>>
>> =A0Just put 4 components and left last empty (if it is same type)?!
>>
>>> Another question I have is how flexible composite columns actually are.
>>> =A0If my data model has a CF containing US zip codes with the following
>>> composite columns:
>>>
>>> {OH:Spring Field} : 45503
>>> {OH:Columbus} : 43085
>>> {FL:Spring Field} : 32401
>>> {FL:Key West} =A0: 33040
>>>
>>> I know I can ask cassandra to "give me the zip codes of all cities in
>>> OH". =A0But can I ask it to "give me the zip codes of all cities named =
Spring
>>> Field" using this model? =A0Thanks.
>>
>> No. You set first composite component at first.
>>
>>
>> I'd use a dynamic CF:
>> row key =3D state abbreviation
>> column name =3D city name
>> column value =3D zip code (or a complex object, one of whose properties =
is
>> zip code)
>>
>> you can iterate over the columns in a single row to get a state's city
>> names and their zip code and you can do a get_range_slices on all keys f=
or
>> the columns starting and ending on the city name to find out the zip cod=
es
>> for a cities with the given name.
>>
>> I think
>>
>> - Chris
>
>