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From Josh Elser <els...@apache.org>
Subject Re: Struggles around Cell#getType()
Date Fri, 27 Oct 2017 16:58:23 GMT
Re-reading https://issues.apache.org/jira/browse/HBASE-8693 that Sergey 
pointed out, I more think that the maybe getType() was misintepreted 
from what Nick originally meant it to be. Maybe intentional, maybe not.

I don't think getTimestamp() should be removed -- when we store multiple 
versions of a Key, users should be able to reconcile the Cells client 
side (e.g. consider a CP which performs some custom merging logic).

getSequenceId() I'd agree probably doesn't belong. getTag() I'll hold 
off judgement because I'm constantly biased into thinking the feature is 
something that it isn't :)

You agree with Ram's suggestion for helper methods as a way forward?

On 10/27/17 7:29 AM, Chia-Ping Tsai wrote:
> The CellBuilder#Data type is introduced to make sure all components used to builder cell
are IA.Public.
> bq. Best as I can tell, Cell#getType() should be deprecated
> As i see it, the Cell#getType, #getTimestamp, #getSequenceId, and #getTag should be deprecated
as these methods is some kind of internal info of storage engine. As a key-value store, the
key  consisting of row, family, and qualifier is enough to the general purpose. Other fields
belong to the specific storage engine, and they should not be in the Cell which is our "frontline"
interface of data.
> On 2017-10-27 06:40, Josh Elser <elserj@apache.org> wrote:
>> Hiya,
>> (Background: see HBASE-19002)
>> In trying to write some example Observers, I found myself in a pickle:
>> how do I tell if a Cell is a Put?
>> * Cell#getType() returns a byte which corresponds to a KeyValue.Type
>> * KeyValue.Type has API to convert a byte to Type
>> * KeyValue (and thus KeyValue.Type) is IA.Private
>> * DataType o.a.h.h.typesDataType _appears to me_ to be the replacement
>> for the KeyValue.Type
>> Best as I can tell, Cell#getType() should be deprecated and we should
>> have some kind of API (method on Cell or CellUtil) which returns a
>> DataType instead of Type. The details of the byte and the KeyValue.Type
>> should be hidden inside the implementation.
>> My hunch is that this is an accidental omission, but Stack recommended
>> that I "ask the class" ;). What have I missed? I think this is trivial
>> to fix; obviously, I don't want to make a fix if I just didn't look hard
>> enough.
>> Thanks!
>> - Josh

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