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From "Chia-Ping Tsai"<chia7...@apache.org>
Subject Re: [DISCUSS] Move Type out of KeyValue
Date Mon, 02 Oct 2017 08:54:16 GMT
How about introducing an new enum "CellType" which is subset of KeyValue#Type? It will be exposed
as IA.Public to end user for helping build the custom cell (via CellBuilder). The types which
"CellType" should have are shown below.
1) Put
2) Delete
3) DeleteFamilyVersion
4) DeleteColumn
5) DeleteFamily
Hence, the CellBuilder#setType(byte) will be replaced by CellBuilder#setType(CellType). Our
internal use still reference to KeyValue#Type.


On 2017-09-29 18:39, Anoop John <anoop.hbase@gmail.com> wrote: 
> Ya as Chia-Ping said, the problem he is trying to solve is very basic
> one. As long as we allow custom Cell creation (Via CellBuilder API)
> and allow Mutations to be added with Cells and pass that from client
> side APIs, we have to make the Type public accessible.
> Or else the Cell building APIs should not be taking in a type byte.
> We have to some way allow user to make put/delete cells stc.
> 
> Is type that bound for only KV?   We have getType in Cell also right?
> The type in full form what we have in KV now, may be making us confuse
> here?  As Ram said it contains some internal types also which the user
> has never to know abt.   Pls correct if saying in wrong way.
> 
> Good that Chia-Ping brought this out here.   We have to either way
> solve it and make the public API fully public.
> 
> -Anoop-
> 
> On Fri, Sep 29, 2017 at 2:27 PM, ramkrishna vasudevan
> <ramkrishna.s.vasudevan@gmail.com> wrote:
> > Even if we are trying to move out I think only few of the types are really
> > user readable. So we should be very careful here. So since we have
> > CellBuilder way it is better we check what type of cells a user can build.
> > I think for now the Cellbuilder is not client exposed?
> > But again moving to Cell means it becomes public which is not right IMO and
> > I thinks others here also agree to it.
> >
> > Regards
> > Ram
> >
> > On Fri, Sep 29, 2017 at 10:50 AM, Chia-Ping Tsai <chia7712@apache.org>
> > wrote:
> >
> >> Thanks for all comment.
> >>
> >> The problem i want to resolve is the valid code should be exposed as
> >> IA.Public. Otherwise, end user have to access the IA.Private class to build
> >> the custom cell.
> >>
> >> For example, I have a use case which plays a streaming role in our
> >> appliaction. It
> >> applies the CellBuilder(HBASE-18519) to build custom cells. These cells
> >> have many same fields so they are put in shared-memory for avoiding GC
> >> pause. Everything is wonderful. However, we have to access the IA.Private
> >> class - KeyValue#Type - to get the valid code of Put.
> >>
> >> I believe there are many use cases of custom cell, and consequently it is
> >> worth adding a way to get the valid type via IA.Public class. Otherwise, it
> >> may imply that the custom cell is based on a unstable way, because the
> >> related code can be changed at any time.
> >> --
> >> Chia-Ping
> >>
> >> On 2017-09-29 00:49, Andrew Purtell <apurtell@apache.org> wrote:
> >> > I agree with Stack. Was typing up a reply to Anoop but let me move it
> >> down
> >> > here.
> >> >
> >> > The type code exposes some low level details of how our current stores
> >> are
> >> > architected. But what if in the future you could swap out HStore
> >> implements
> >> > Store with PStore implements Store, where HStore is backed by HFiles and
> >> > PStore is backed by Parquet? Just as a hypothetical example. I know there
> >> > would be larger issues if this were actually attempted. Bear with me. You
> >> > can imagine some different new Store implementation that has some
> >> > advantages but is not a design derived from the log structured merge tree
> >> > if you like. Most values from a new Cell.Type based on KeyValue.Type
> >> > wouldn't apply to cells from such a thing because they are particular to
> >> > how LSMs work. I'm sure such a project if attempted would make a number
> >> of
> >> > changes requiring a major version increment and low level details could
> >> be
> >> > unwound from Cell then, but if we could avoid doing it in the first
> >> place,
> >> > I think it would better for maintainability.
> >> >
> >> >
> >> > On Thu, Sep 28, 2017 at 9:39 AM, Stack <stack@duboce.net> wrote:
> >> >
> >> > > On Thu, Sep 28, 2017 at 2:25 AM, Chia-Ping Tsai <chia7712@apache.org>
> >> > > wrote:
> >> > >
> >> > > > hi folks,
> >> > > >
> >> > > > User is allowed to create custom cell but the valid code of type
-
> >> > > > KeyValue#Type - is declared as IA.Private. As i see it, we should
> >> expose
> >> > > > KeyValue#Type as Public Client. Three possible ways are shown
below:
> >> > > > 1) Change declaration of KeyValue#Type from IA.Private to IA.Public
> >> > > > 2) Move KeyValue#Type into Cell.
> >> > > > 3) Move KeyValue#Type to upper level
> >> > > >
> >> > > > Any suggestions?
> >> > > >
> >> > > >
> >> > > What is the problem that we are trying to solve Chia-Ping? You want
to
> >> make
> >> > > Cells of a new Type?
> >> > >
> >> > > My first reaction is that KV#Type is particular to the KV
> >> implementation.
> >> > > Any new Cell implementation should not have to adopt the KeyValue
> >> typing
> >> > > mechanism.
> >> > >
> >> > > S
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > > --
> >> > > > Chia-Ping
> >> > > >
> >> > > >
> >> > >
> >> >
> >> >
> >> >
> >> > --
> >> > Best regards,
> >> > Andrew
> >> >
> >> > Words like orphans lost among the crosstalk, meaning torn from truth's
> >> > decrepit hands
> >> >    - A23, Crosstalk
> >> >
> >>
> 

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