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From Soumya Acharya <cse.sou...@gmail.com>
Subject Re: Data Model
Date Thu, 13 Sep 2012 17:59:07 GMT
I just started learning Cassandra any suggestion where to start with ??


Thanks
Soumya

On Thu, Sep 13, 2012 at 10:54 AM, Roshni Rajagopal <
roshni_rajagopal@hotmail.com> wrote:

>  I want to learn how we can model a mix of static and dynamic columns in
> a family.
>
> Consider a course_students col family which gives a list of students for a
> course
> with row key- Course Id
> Columns - Name, Teach_Nm, StudID1, StudID2, StudID3
> Values - Maths, Prof. Abc, 20,21,25
> where 20,21,25 are IDs of students.
>
> We have
>
> fixed columns like Course Name, Teacher Name, and a dynamic number of
>
> columns like 'StudID1', 'StudID2' etc, and my thoughts were that we could
>
> look for 'StudID' and get all the columns with the student Ids in Hector.
> But the
>
> question was how would we determine the number for the column, like to add
>
> StudID3 we need to read the row and identify that 2 students are there,
>
> and this is the third one.
>
>
> So we can remove the number in the column name, altogether and keep
>
> columns like Course Name, Teacher Name, Student:20,Student:21, Student:25,
>
> where the second part is the actual student id. However here we run into
>
> the second issue that we cannot have some columns of a composite format
>
> and some of another format, when we use static column families- all
>
> columns would need to be in the format UTF8:integer We may want to treat
>
> it as a composite column key and not use a delimiter- to get sorting,
>
> validate the types of the parts of the key, not have to search for the
>
> delimiter and separate the 2 components  manually etc.
>
>
> A third option is to put only data in the column name for students like
>
> Course Name, Teacher Name, 20,21,25 - it would be difficult to identify
>
> that columns with name 20, 21, 25 actually stand for student names - a bit
>
> unreadable.
>
>
> I hope this is not confusing, and would like to hear your thoughts on this.The
> question is
>
> around when you de-normalize & want to have some static info like name ,
>
> and a dynamic list - whats the best way to model this.
>
>
> Regards,
>
> Roshni
>



-- 
Regards and Thanks
Soumya Kanti Acharya

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