I agree with Peter. I typically keep in Cassandra just the data that will benefit from it's distribution and replication capabilities. Most of the applications in which I use Cassandra also use a relational DB, so best tool for the job type of approach.
And for the PK it's implied; some identifiers are temporal, some others are not, PK should use non-temporal ones, e.g. phones and addresses are a bad idea, SSNs might be ok but in general for C* synthetic PK are best, e.g. UUIDs or TimeUUIDs. On Sat, Feb 28, 2015 at 8:42 AM, Peter Lin <wool...@gmail.com> wrote: > > Hate to be the one to point this out, but that is not the ideal use case > for Cassandra. > > If you really want to brute force it and "make it fit" cassandra, the > easiest way is to create a class called Index. The index class would have > name, phone and address fields. The hashcode and equals method would need > to be overrided. Basically the same rules that apply to HashMap keys. Once > you have that, you can use "if not exists" in the insert. > > Here's the risk though. What happens when the phone and address changes? > The hashcode and equals will fail and queries will fail. This is a general > anti-pattern for anything that uses Maps and is mutable. This is the reason > the default object hashCode in java is system assigned and there's all > sorts of warnings about overriding hashCode and equals. > > The only case where this works correctly is immutable databases or > temporal databases. I would strongly advise against using a key that is a > compound of name+phone+address. If the system needs to perform updates, the > key needs to be immutable so that queries won't fail. > > On Sat, Feb 28, 2015 at 10:18 AM, Brian Sam-Bodden < > bsbod...@integrallis.com> wrote: > >> As far as I know there is no such thing. You could make that value a >> single PK for the table therefore guaranteeing uniqueness and check on >> insert with `IF NOT EXISTS` to prevent dups. Of course that works just for >> one value, if you have multiple values a compound PK will still let dups in >> for a given column. So a different data model might be the answer there. If >> the values in those columns can be enumerated then you could always create >> a bitmask for the collection of values of the must-be-unique columns and >> use that as park of your PK. If they ranges are too broad then maybe some >> sort of hash made up of the values that need to be unique would be my next >> attempt. >> >> You could also simply enforce the uniqueness programmatically but that >> will require a read-before-you-write approach. Three is also the >> possibility of using a Cassandra trigger (but I heard they are dangerous >> and might not buy you anything more than the client-side programmatic >> approach) >> >> Cheers, >> Brian >> http://integrallis.com >> >> On Fri, Feb 27, 2015 at 9:29 PM, ROBIN SRIVASTAVA < >> srivastava.robi...@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 >>> >>> example : 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. >>> >> >> >> >> -- >> Cheers, >> Brian >> http://www.integrallis.com >> > > -- Cheers, Brian http://www.integrallis.com
