Yokozuna and Bucket Types

[rzezeski]

basho/riak#362

Add bucket type support to Yokozuna.

Yokozuna will:

• Continue to base index association on bucket properties.
• If the bucket is under the default type then the bucket prop yz_index must be set. This is also the scenario for users migrating from Riak Search.
• If the bucket has a type with yz_index set then that bucket will inherit that index association.
• If the bucket has a type with yz_index set but also has yz_index set as a bucket prop then the latter wins. This means buckets under one type can point to different indexes.
• Multiple buckets can point to one index.
• A bucket can only have one associated index.
• When migrating Riak Search indexes keep them under default type as to avoid moving the KV data.
• Add logic to yz_index:associated_buckets(Index) to understand types. I.e. if a type has yz_index set and has 3 buckets underneath it then those 3 buckets, along with any other buckets pointing to Index, should be returned.
• Add special field _yz_bt to designate the bucket type of the Solr document.

[rzezeski]

After talking with @jrwest tonight it sounds like get_bucket will handle the property inheritance automatically. I.e. Yokozuna doesn't have to care where the index name comes from. It's up to the user to know that a type property applies to all its buckets but can be overridden by a bucket property.

It sounds like yz_index:associated_buckets could be a problem. Perhaps the best thing to do there is just return any types with yz_index set along with and bucket overrides. E.g.

-spec assocaited(Index) -> [{type, [type_name()]}, {buckets, [bucket_name()]}].

[jrwest]

one thing I forgot to mention when talking about this earlier is get_bucket can now return {error, no_type} when passed {BucketType, BucketName} and BucketType d.n.e (or is inactive)

[rzezeski]

This will rely on basho/riak_kv#711.