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From: Dan Halperin <dhalperi@google.com.INVALID>
Date: Wed, 23 Mar 2016 13:56:32 -0700
Message-ID: 
 <CAA8k_F+q3ycMZkOgmrGvUrz6g=UePsb81FrgnyEy8xvjPsNE8A@mail.gmail.com>
Subject: Re: Capability matrix question
To: dev@beam.incubator.apache.org
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+1 @Amit =3D>  -1 to Counter but +1 to Metric.

On Wed, Mar 23, 2016 at 1:43 PM, Amit Sela <amitsela33@gmail.com> wrote:

> IMHO Counters just count..  Metrics measure things, so I think metrics
> sounds better. Accumulators and Aggregators would have been good as well =
if
> they weren't so overloaded.
> That's just my thoughts here though..
>
> On Wed, Mar 23, 2016 at 10:38 PM Robert Bradshaw
> <robertwb@google.com.invalid> wrote:
>
> > +1 to renaming this. [P]Counter is another option.
> >
> > On Wed, Mar 23, 2016 at 9:12 AM, Kenneth Knowles <klk@google.com.invali=
d
> >
> > wrote:
> > > +1 to considering "metric" / PMetric / etc.
> > >
> > > On Wed, Mar 23, 2016 at 8:09 AM, Amit Sela <amitsela33@gmail.com>
> wrote:
> > >
> > >> How about "PMetric" ?
> > >>
> > >> On Wed, Mar 23, 2016, 16:53 Frances Perry <fjp@google.com> wrote:
> > >>
> > >>>
> > >>>>> Perhaps I'm unclear on what an =E2=80=9CAggregator=E2=80=9D is. I=
 assumed that a
> line
> > >>>>> such as the following:
> > >>>>>
> > >>>>> PCollection<KV<String, Double>> meanByName =3D
> > >>>>> dataPoints.apply(Mean.<String, Double>perKey());
> > >>>>>
> > >>>>> =E2=80=A6would be considered an Aggregator, since it applies a me=
an
> > aggregation
> > >>>>> over a window. Is that correct, with respect to the Beam
> > terminology? If
> > >>>>> not, what would an example of an Aggregator be?
> > >>>>>
> > >>>>
> > >>> Ah, we may have some slightly confusing terminology here.
> > >>>
> > >>> In that code snippet you are using a PTransform (Mean.perKey) to
> > combine
> > >>> a PCollection using the Mean CombineFn
> > >>> <
> >
> https://github.com/apache/incubator-beam/blob/c199f085473cfcd79014d0a022b=
5ce3fdd4863ec/sdk/src/main/java/com/google/cloud/dataflow/sdk/transforms/Co=
mbine.java#L359
> > >.
> > >>> An Aggregator
> > >>> <
> >
> https://github.com/apache/incubator-beam/blob/211e76abf9ba34c35ef13cca279=
cbeefdad7c406/sdk/src/main/java/com/google/cloud/dataflow/sdk/transforms/Ag=
gregator.java#L54
> > >
> > >>> takes a CombineFn and applies it continuously within a DoFn. So it'=
s
> > more
> > >>> analogous to a 'counter'. You can see an example of aggregators in
> > >>> DebuggingWordCount
> > >>> <
> >
> https://github.com/apache/incubator-beam/blob/master/examples/src/main/ja=
va/com/google/cloud/dataflow/examples/DebuggingWordCount.java#L129
> > >
> > >>> .
> > >>>
> > >>> We never really used the term *aggregation *to refer to a general s=
et
> > of
> > >>> PTransforms until we started describing things to the community. Bu=
t
> > it is
> > >>> a useful word, so we've ended up in a bit of confusing state. Maybe
> we
> > >>> should consider renaming Aggregator? Something like "metric" might =
be
> > >>> clearer.
> > >>>
> > >>>
> >
>

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