if kryo could transparently be used for subtrees without narrowing the implicit that would be great
On Wed, Oct 26, 2016 at 5:10 PM, Koert Kuipers <ko...@tresata.com> wrote: > i use kryo for the whole thing currently > > it would be better to use it for the subtree > > On Wed, Oct 26, 2016 at 5:06 PM, Michael Armbrust <mich...@databricks.com> > wrote: > >> You use kryo encoder for the whole thing? Or just the subtree that we >> don't have specific encoders for? >> >> Also, I'm saying I like the idea of having a kryo fallback. I don't see >> the point of narrowing the the definition of the implicit. >> >> On Wed, Oct 26, 2016 at 1:07 PM, Koert Kuipers <ko...@tresata.com> wrote: >> >>> for example (the log shows when it creates a kryo encoder): >>> >>> scala> implicitly[EncoderEvidence[Option[Seq[String]]]].encoder >>> res5: org.apache.spark.sql.Encoder[Option[Seq[String]]] = >>> class[value[0]: array<string>] >>> >>> scala> implicitly[EncoderEvidence[Option[Set[String]]]].encoder >>> dataframe.EncoderEvidence$: using kryo encoder for >>> scala.Option[Set[String]] >>> res6: org.apache.spark.sql.Encoder[Option[Set[String]]] = >>> class[value[0]: binary] >>> >>> >>> >>> >>> On Wed, Oct 26, 2016 at 4:00 PM, Koert Kuipers <ko...@tresata.com> >>> wrote: >>> >>>> why would generating implicits for ProductN where you also require the >>>> elements in the Product to have an expression encoder not work? >>>> >>>> we do this. and then we have a generic fallback where it produces a >>>> kryo encoder. >>>> >>>> for us the result is that say an implicit for Seq[(Int, Seq[(String, >>>> Int)])] will create a new ExpressionEncoder(), while an implicit for >>>> Seq[(Int, Set[(String, Int)])] produces a Encoders.kryoEncoder() >>>> >>>> On Wed, Oct 26, 2016 at 3:50 PM, Michael Armbrust < >>>> mich...@databricks.com> wrote: >>>> >>>>> Sorry, I realize that set is only one example here, but I don't think >>>>> that making the type of the implicit more narrow to include only ProductN >>>>> or something eliminates the issue. Even with that change, we will fail to >>>>> generate an encoder with the same error if you, for example, have a field >>>>> of your case class that is an unsupported type. >>>>> >>>>> Short of changing this to compile-time macros, I think we are stuck >>>>> with this class of errors at runtime. The simplest solution seems to be >>>>> to >>>>> expand the set of thing we can handle as much as possible and allow users >>>>> to turn on a kryo fallback for expression encoders. I'd be hesitant to >>>>> make this the default though, as behavior would change with each release >>>>> that adds support for more types. I would be very supportive of making >>>>> this fallback a built-in option though. >>>>> >>>>> On Wed, Oct 26, 2016 at 11:47 AM, Koert Kuipers <ko...@tresata.com> >>>>> wrote: >>>>> >>>>>> yup, it doesnt really solve the underlying issue. >>>>>> >>>>>> we fixed it internally by having our own typeclass that produces >>>>>> encoders and that does check the contents of the products, but we did >>>>>> this >>>>>> by simply supporting Tuple1 - Tuple22 and Option explicitly, and not >>>>>> supporting Product, since we dont have a need for case classes >>>>>> >>>>>> if case classes extended ProductN (which they will i think in scala >>>>>> 2.12?) then we could drop Product and support Product1 - Product22 and >>>>>> Option explicitly while checking the classes they contain. that would be >>>>>> the cleanest. >>>>>> >>>>>> >>>>>> On Wed, Oct 26, 2016 at 2:33 PM, Ryan Blue <rb...@netflix.com> wrote: >>>>>> >>>>>>> Isn't the problem that Option is a Product and the class it contains >>>>>>> isn't checked? Adding support for Set fixes the example, but the problem >>>>>>> would happen with any class there isn't an encoder for, right? >>>>>>> >>>>>>> On Wed, Oct 26, 2016 at 11:18 AM, Michael Armbrust < >>>>>>> mich...@databricks.com> wrote: >>>>>>> >>>>>>>> Hmm, that is unfortunate. Maybe the best solution is to add >>>>>>>> support for sets? I don't think that would be super hard. >>>>>>>> >>>>>>>> On Tue, Oct 25, 2016 at 8:52 PM, Koert Kuipers <ko...@tresata.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> i am trying to use encoders as a typeclass where if it fails to >>>>>>>>> find an ExpressionEncoder it falls back to KryoEncoder. >>>>>>>>> >>>>>>>>> the issue seems to be that ExpressionEncoder claims a little more >>>>>>>>> than it can handle here: >>>>>>>>> implicit def newProductEncoder[T <: Product : TypeTag]: >>>>>>>>> Encoder[T] = Encoders.product[T] >>>>>>>>> >>>>>>>>> this "claims" to handle for example Option[Set[Int]], but it >>>>>>>>> really cannot handle Set so it leads to a runtime exception. >>>>>>>>> >>>>>>>>> would it be useful to make this a little more specific? i guess >>>>>>>>> the challenge is going to be case classes which unfortunately dont >>>>>>>>> extend >>>>>>>>> Product1, Product2, etc. >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Ryan Blue >>>>>>> Software Engineer >>>>>>> Netflix >>>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >> >
