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From aaron morton <aa...@thelastpickle.com>
Subject Re: Trying to avoid super columns
Date Fri, 13 Apr 2012 01:57:16 GMT
If this is write once read many data you may get some benefit from packing all the info for
a product into one column, using something like JSON for the column value. 

>> The one thing that stands out to me with this approach is the number of additonal
columns that will be created for a single key. Will the increase in columns, create new issues
I will need to deal with?
Millions of columns in a row may be ok, depending on the types of queries you want to run
(some background http://thelastpickle.com/2011/07/04/Cassandra-Query-Plans/) 

The more important issue is the byte size of the row. Wide rows take longer to compact and
repair, and I try to avoid rows above a few 10's of MB. By default rows larger than 64MB require
slower compaction. 

Compression in 1.X will help where you have lots of repeating column names. 

Cheers


-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 13/04/2012, at 7:32 AM, Dave Brosius wrote:

> If you want to reduce the number of columns, you could pack all the data for a product
into one column, as in
> 
> 
> composite column name-> product_id_1:12.44:1.00:3.00
> 
> 
> 
> On 04/12/2012 03:03 PM, Philip Shon wrote:
>> I am currently working on a data model where the purpose is to look up multiple products
for given days of the year.  Right now, that model involves the usage of a super column family.
e.g.
>> 
>> "2012-04-12": {
>>  "product_id_1": {
>>    price: 12.44,
>>    tax: 1.00,
>>    fees: 3.00,
>>  },
>>  "product_id_2": {
>>    price: 50.00,
>>    tax: 4.00,
>>    fees: 10.00
>>  }
>> }
>> 
>> I should note that for a given day/key, we are expecting in the range of 2 million
to 4 million products (subcolumns).
>> 
>> With this model, I am able to retrieve any of the products for a given day using
hector's MultigetSuperSliceQuery.
>> 
>> 
>> I am looking into changing this model to use Composite column names. How would I
go about modeling this? My initial thought is to migrate the above model into something more
like the following.
>> 
>> "2012-04-12": {
>>  "product_id_1:price": 12.44,
>>  "product_id_1:tax": 1.00,
>>  "product_id_1:fees": 3.00,
>>  "product_id_2:price": 50.00,
>>  "product_id_2:tax": 4.00,
>>  "product_id_2:fees": 10.00,
>> }
>> 
>> The one thing that stands out to me with this approach is the number of additonal
columns that will be created for a single key. Will the increase in columns, create new issues
I will need to deal with?
>> 
>> Are there any other thoughts about if I should actually move forward (or not) with
migration this super column family to the model with the component column names?
>> 
>> Thanks,
>> 
>> Phil
> 


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