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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: How should clients handle the user defined types in 2.1?
Date Tue, 25 Feb 2014 11:10:10 GMT
>
>
> Is there any documentation on how CQL clients should handle the new user
> defined types coming in 2.1? There's nothing in the protocol specification
> on how to handle custom types as far as I can see.
>

Can't say there is much documentation so far for that. As for the spec, it
was written in a time where user defined types didn't existed and so as far
as the protocol is concerned so far, user defined types are handled by the
protocol as a "custom type", i.e the full internal class is returned. And
so ...


>
> For example, I tried creating the "address" type from the description of
> CASSANDRA-5590, and this is how its metadata looks (the metadata for a
> query contains a column with a custom type and this is the description of
> it):
>
>
> org.apache.cassandra.db.marshal.UserType(user_defined_types,61646472657373,737472656574:org.apache.cassandra.db.marshal.UTF8Type,63697479:org.apache.cassandra.db.marshal.UTF8Type,7a69705f636f6465:org.apache.cassandra.db.marshal.Int32Type,70686f6e6573:org.apache.cassandra.db.marshal.SetType(org.apache.cassandra.db.marshal.UTF8Type))
>
> Is the client supposed to parse that description, and in that case how?
>

... yes, for now you're supposed to parse that description. Which is not
really much documented outside of looking up the Cassandra code, but I can
tell you that the first parameter of the UserType is the keyspace name the
type has been defined in, the second is the type name hex encoded, and the
rest is list of fields and their type. Each field name is hex encoded and
separated from it's type by ':'. And that's about it.

We will introduce much shorted definitions in the next iteration of the
native protocol, but it's yet unclear when that will happen.

--
Sylvain

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