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From samal <samalgo...@gmail.com>
Subject Re: Data Modeling- another question
Date Tue, 28 Aug 2012 07:37:10 GMT
yes, you are right, it depend on use cases.
I suggested it is a better choice not only choice. JSON will be better if
any filed change re-write whole data without reading.
I tend to use JSON more, where my data does not change or very rarely, Like
storing demoralized JSON data for analytic purpose.
I prefer CF and [:scoped] method for frequently updating filed.
{
this.user.cart.category.p1.name:''
this.user.cart.category.p1.unit:''
this.user.cart.category.p1.desc:''
this.user.cart.category.p2.name:''
this.user.cart.category.p2.unit:''
this.user.cart.category.p2.desc:''
}

Yes you are right, Its really about understating app data and its behavior,
not JSON or column, according to that designing DM.

On Tue, Aug 28, 2012 at 12:20 PM, Guy Incognito <dnd1066@gmail.com> wrote:

>  i would respectfully disagree, what you have said is true but it really
> depends on the use case.
>
> 1) do you expect to be doing updates to individual fields of an item, or
> will you always update all fields at once?  if you are doing separate
> updates then the first is definitely easier to handle updates.
> 2) do you expect to do paging of the list?  this will be easier with the
> json approach, as in the first your item may span across a page boundary -
> not an insurmountable problem by any means, but more complicated
> nonetheless.  this is not
> an issue obviously if all your items have the same number of fields.
> 3) do you expect to read or delete multiple items individually?  you may
> have to do multiple reads/deletes of a row if the items are not adjacent to
> each other as you cannot do 'disjoint' slices of columns at the moment.
> with the json approach you can just specify individual columns and you're
> done.  again this is less of an issue if items have a known set of fields,
> but your list of columns to read/delete may get quite large fairly quickly
>
> the first is definitely better if you want to update individual fields,
> read-then-write is not a good idea in cassandra.  but it is more
> complicated for most usage scenarios, so you have to work out if you really
> need the extra flexibility.
>
>
> On 24/08/2012 13:54, samal wrote:
>
> First is better choice, each filed can be updated separately(write only).
> Second you have to take care json yourself (read first-modify-then write).
>
> On Fri, Aug 24, 2012 at 5:45 PM, Roshni Rajagopal <
> Roshni.Rajagopal@wal-mart.com> wrote:
>
>> Hi,
>>
>> Suppose I have a column family to associate a user to a dynamic list of
>> items. I want to store 5-10 key  information about the item, & no specific
>> sorting requirements are there.
>> I have two options
>>
>> A) use composite columns
>> UserId1 : {
>>  <itemid1>:<Name> = Betty Crocker,
>>  <itemid1>:<Descr> = Cake
>> <itemid1>:<Qty> = 5
>>  <itemid2>:<Name> = Nutella,
>>  <itemid2>:<Descr> = Choc spread
>> <itemid2>:<Qty> = 15
>> }
>>
>> B) use a json with the data
>> UserId1 : {
>>  <itemid1> = {name: Betty Crocker,descr: Cake, Qty: 5},
>>  <itemid2> ={name: Nutella,descr: Choc spread, Qty: 15}
>> }
>>
>> Which do you suggest would be better?
>>
>>
>> Regards,
>> Roshni
>>
>> This email and any files transmitted with it are confidential and
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>>
>
>
>

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