Hi,
+1 for ForwardedFields. I like it much more than ConstantFields.
I think it makes it clear what the feature does.
It's a very cool feature and indeed not advertised a lot. I use it when I
remember, but most of the times I forget it exists ;)
-V.
On 23 January 2015 at 22:12, Fabian Hueske <fhue...@gmail.com> wrote:
> Hi all,
>
> I have a pending pull request (#311) to fix and enable semantic information
> for functions with nested and Pojo types.
> Semantic information is used to tell the optimizer about the behavior of
> user-defined functions.
> The optimizer can use this information to generate more efficient execution
> plans.
>
> Assume for example a data set which is partitioned on the first field of a
> tuple and which is given to a Map function. If the optimizer knows, that
> the Map function does not modify the first field, it can infer that the
> data is still partitioned after the Map function was applied.
>
> There are two ways to give semantic information for user-defined function:
> 1) Class annotations:
> @ConstantFields("0; 1->2")
> public class MyMapper extends MapFunction<...> { }
>
> 2) Inline data flow:
> data.map(new MapFunction<...>() {...}).witConstantSet("0; 1->2");
>
> In both cases the semantic annotation indicates that the first field (0) is
> preserved and the second field of the input (1) is forwarded to the third
> field of the output (2).
>
> The question is how should we name this feature?
> Right now it is inconsistently called "ConstantField" and "ConstantSet".
>
> I would prefer the name ForwardedFields because this indicates that fields
> are "forwarded" through the function and possibly also moved to another
> location. It would however, change the API (although I don't think this
> feature is often used because it was not advertised a lot).
>
> Any other suggestions or opinions on this?
>
> Cheers, Fabian
>
