Use a RDBMS 

There is a reason constraints were created and why Cassandra doesn't have it

Sent from my iPhone

On Mar 2, 2015, at 2:23 AM, Rahul Srivastava <srivastava.robin71@gmail.com> wrote:

but what if i want to fetch the value using on table then this idea might fail

On Mon, Mar 2, 2015 at 12:46 PM, Ajaya Agrawal <ajku.agr@gmail.com> wrote:
Make a table for each of the unique keys. For e.g.

If primary key for user table is user_id and you want the phone number column to be unique then create another table wherein the primary key is (phone_number, user_id). Before inserting to main table try to insert to this table first with "if not exists" clause. If it succeeds then go ahead with your insert to the user table. Similarly while deleting a row from the primary table delete the corresponding row in all other tables. The order of insertion to tables matter here otherwise you would end up inducing race conditions.

The catch here is, you should not be updating the unique column ever. If you do that you would have to use locks and if there are multiple nodes running your application then you would need a distributed lock. I would suggest not to update the unique columns. In stead force your users to delete the entry and recreate it. If you can't do that you need to evaluate your choice of database. Perhaps a relational database would be better suited to your requirements.

Hope this helps!

-Ajaya

Cheers,
Ajaya

On Fri, Feb 27, 2015 at 5:26 PM, ROBIN SRIVASTAVA <srivastava.robin71@gmail.com> wrote:

I want to make unique constraint in cassandra . As i want that all the value in my column be unique in my column family ex: name-rahul phone-123 address-abc

now i want that in this row no values equal to rahul ,123 and abc get inserted again on searching on datastax i found that i can achieve it by doing query on partition key as IF NOT EXIST ,but not getting the solution for getting all the three values unique means if name- jacob phone-123 address-qwe

this should also be not inserted into my database as my phone column has the same value as i have shown with name-rahul.