CODEWITHSUNDEEP
constraintsuniquecassandra-2.0
user3467525
user3467525

Reputation: 71

How to make values unique in cassandra

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

now i want that i this row no values equal to rahul ,123 and abc get inserted again on seraching 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 3 values uniques 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.

Upvotes: 3

Views: 5073

Answers (2)

Ronald Currier
Ronald Currier

Reputation: 585

I know this is an old question and the existing answer is correct (you can't do constraints in C*), but you can solve the problem using batched creates. Create one or more additional tables, each with the constrained column as the primary key and then batch the creates, which is an atomic operation. If any of those column values already exist the entire batch will fail. For example if the table is named Foo, also create Foo_by_Name (primary key Name), Foo_by_Phone (primary key Phone), and Foo_by_Address (primary key Address) tables. Then when you want to add a row, create a batch with all 4 tables. You can either duplicate all of the columns in each table (handy if you want to fetch by Name, Phone, or Address), or you can have a single column of just the Name, Phone, or Address.

Upvotes: 1

Roman Tumaykin
Roman Tumaykin

Reputation: 1931

The short answer is that constraints of any type are not supported in Cassandra. They are simply too expensive as they must involve multiple nodes, thus defeating the purpose of having eventual consistency in first place. If you needed to make a single column unique, then there could be a solution, but not for more unique columns. For the same reason - there is no isolation, no consistency (C and I from the ACID). If you really need to use Cassandra with this type of enforcement, then you will need to create some kind of synchronization application layer which will intercept all requests to the database and make sure that the values are unique, and all constraints are enforced. But this won't have anything to do with Cassandra.

Upvotes: 5

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