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From Yogi Devendra <yogideven...@apache.org>
Subject Re: Projection Operator in Malhar
Date Thu, 10 Mar 2016 05:37:33 GMT
@Priyanka

Projection is standard term from relational algebra
https://en.wikipedia.org/wiki/Projection_(relational_algebra)

+1 for the name projection.

~ Yogi

On 10 March 2016 at 11:01, Priyanka Gugale <priyanka@datatorrent.com> wrote:

> +1.
>
> This name is not self explanatory, I can't think of anything better as of
> now. If someone have suggestions please add it here. I will also try to
> find some options.
>
> -Priyanka
>
> On Thu, Mar 10, 2016 at 10:17 AM, Sandeep Deshmukh <
> sandeep@datatorrent.com>
> wrote:
>
> > + 1 on projection w/o adding or updating fields. IMO, the purpose is to
> > split the record into something that is useful and something that is not.
> >
> > Regards,
> > Sandeep
> >
> > On Wed, Mar 9, 2016 at 9:08 PM, Chinmay Kolhatkar <chinmay@apache.org>
> > wrote:
> >
> > > +1 for projection operator.
> > >
> > > @Sandesh, Adding of new fields and updating will be done as a part of
> > > Enricher and Transform operator respectively.
> > > I've sent another mail about Transform operator before.
> > >
> > >
> > > On Wed, Mar 9, 2016 at 8:54 PM, Sandesh Hegde <sandesh@datatorrent.com
> >
> > > wrote:
> > >
> > > > +1
> > > >
> > > > Adding of new fields and updating of fields can be part of this?
> > > >
> > > > On Wed, Mar 9, 2016, 5:50 AM Pradeep A. Dalvi <prad@apache.org>
> wrote:
> > > >
> > > > > Dear Folks,
> > > > >
> > > > > We are creating Projection Operator which will allow apex users to
> > > > project
> > > > > (select/drop) certain fields from the incoming tuples. This
> operation
> > > > might
> > > > > be done unconditionally or based on certain condition.
> > > > >
> > > > > Use case:
> > > > > -------------
> > > > > Not all fields of tuples are of interest for the downstream
> > operators.
> > > In
> > > > > such cases, one may want project selective fields to downstream.
> Also
> > > one
> > > > > may want to drop few fields, instead of selecting many.
> > > > > In certain scenarios, one may want to project certain fields based
> on
> > > > given
> > > > > condition or expression.
> > > > >
> > > > > Functionality:
> > > > > -----------------
> > > > > 1. Projection operator shall receive POJO as input tuple and emit
2
> > > POJOs
> > > > > on separate output ports i.e. selected and dropped. Selected output
> > > port
> > > > > shall emit POJO with selected fields and dropped output shall emit
> > POJO
> > > > of
> > > > > dropped fields.
> > > > > 2. Operator needs select or drop fields as input params. This shall
> > be
> > > > > specified using comma separated list of fields.
> > > > > 3. Operator shall emit POJO only on connected output ports. In
> > another
> > > > > words, if dropped output port is not connected, it shall not even
> try
> > > to
> > > > > generate POJOs with dropped fields.
> > > > >
> > > > > Please feel free to let me know your thoughts on this.
> > > > >
> > > > > Thanks,
> > > > > Pradeep A. Dalvi
> > > > >
> > > >
> > >
> >
>

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