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From Alfonso Nishikawa <alfonso.nishik...@gmail.com>
Subject Re: Updated GORA-174 HBase information - unions
Date Sun, 10 Feb 2013 21:06:28 GMT
Hi Renato,

> So what you are proposing is to store and extra index at the beginning
> of the actual value? or does HBase do this automatically? What about
> if bytes were being written? couldn't some type of corruption happen
> and make this unusable?

The extra byte at the beginning of the actual value is part of Avro :)
Gora-hbase must adhere to avro specs, so that is really the union
sourcecode update.
In the case of bytes, first is encoded a 'long' with the length of the
bytes, followed with the bytes data.
I got all from Avro Specs at [2].

>> think now is better expressed.
>> If no one think is wrong, I will implement solution-1 and solution-2(this
>> means maybe quite work, so do we maintain it? -I vote yes).
>
> So does your solution have two parts? or are they two separate
> possible solutions?

There are two potencial different problems (incompatibilities with
legacy data), so we can choose to leave them behind both, only one, or
none. Lewis voted for facing both (same as I), so I guess we will
mainaint data compatibility until version 1.0.

> You said on another email that HBase could persist Union data types
> directly without having to modify it (did I get that right? or am I
> confusing stuff? ) so implementing this would be just to tell HBase to
> save the union data type but not actually writing this extra byte? I
> wasn't able to find the avro documentation talking about this, could
> you please point me to where this is?

Sorry, surely my fault because I always express myself wrong. You need
to write that index. Solution 1 [3] avoids writing that index but is
an exception for only null-or-onetype unions.

>> I had to restore my git server, but in this case not all went right, so now
>> is up again at [1].
>
> Thanks! and great work documenting this issue! (:
>
>
> Renato M.

Thank you for your comments and questions! :)

Best regards,

Alfonso Nishikawa

[2] - http://avro.apache.org/docs/current/spec.html#binary_encoding
[3] - https://people.apache.org/~alfonsonishikawa/gora-174.html

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