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From Ryan Blue <rb...@cloudera.com>
Subject Re: [common type encoding breakout] Re: HBase Hackathon @ Salesforce 05/06/2014 notes
Date Mon, 09 Jun 2014 20:13:23 GMT
On 06/08/2014 05:13 PM, James Taylor wrote:
> Couple items I didn't see mentioned, but I think would be good to get
> clarity on:
> * variable length DECIMAL (Phoenix relies on this)

Did you send a description of Phoenix's current implementation? I can't 
find it in my inbox.

> * ARRAY type (Phoenix supports this - arrays of fixed width data is
> just concatenated together, while arrays of variable length data is
> run-length-encoded with a double null byte terminator followed by an
> index of the start position of each element )

Arrays are delegated to protobuf, which has two formats. The first is a 
repeated tag and value, the second is a packed format with the data 
field concatenated.

> * Optional use of mem comparable composite row key as the value of a
> KeyValue (I think this makes things easier).

The problem with this is that it isn't a tagged format, so schema 
evolution isn't possible without resolving the read and write schemas. I 
think we should plan on sticking to protobuf because we can always read 
the data with the current schema.

rb

-- 
Ryan Blue
Software Engineer
Cloudera, Inc.

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