And the result is essentially a cross product of all the different array elements?
On Thu, Jan 14, 2021 at 11:25 AM Robert Bradshaw <rober...@google.com> wrote: > I think it makes sense to allow specifying more than one, if desired. This > is equivalent to just stacking multiple Unnests. (Possibly one could even > have a special syntax like "*" for all array fields.) > > On Thu, Jan 14, 2021 at 10:05 AM Reuven Lax <re...@google.com> wrote: > >> Should Unnest be allowed to specify multiple array fields, or just one? >> >> On Wed, Jan 13, 2021 at 11:59 PM Manninger, Matyas < >> matyas.mannin...@veolia.com> wrote: >> >>> I would also not unnest arrays nested in arrays just the top-level array >>> of the specified fields. >>> >>> On Wed, 13 Jan 2021 at 20:58, Reuven Lax <re...@google.com> wrote: >>> >>>> Nested fields are not part of standard SQL AFAIK. Beam goes further and >>>> supports array of array, etc. >>>> >>>> On Wed, Jan 13, 2021 at 11:42 AM Kenneth Knowles <k...@apache.org> >>>> wrote: >>>> >>>>> Just the fields specified, IMO. When in doubt, copy SQL. (and I mean >>>>> SQL generally, not just Beam SQL) >>>>> >>>>> Kenn >>>>> >>>>> On Wed, Jan 13, 2021 at 11:17 AM Reuven Lax <re...@google.com> wrote: >>>>> >>>>>> Definitely could be a top-level transform. Should it automatically >>>>>> unnest all arrays, or just the fields specified? >>>>>> >>>>>> We do have to define the semantics for nested arrays as well. >>>>>> >>>>>> On Wed, Jan 13, 2021 at 10:57 AM Robert Bradshaw <rober...@google.com> >>>>>> wrote: >>>>>> >>>>>>> Ah, thanks for the clarification. UNNEST does sound like what you >>>>>>> want here, and would likely make sense as a top-level relational >>>>>>> transform >>>>>>> as well as being supported by SQL. >>>>>>> >>>>>>> On Wed, Jan 13, 2021 at 10:53 AM Tao Li <t...@zillow.com> wrote: >>>>>>> >>>>>>>> @Kyle Weaver <kcwea...@google.com> sure thing! So the input/output >>>>>>>> definition for the Flatten.Iterables >>>>>>>> <https://beam.apache.org/releases/javadoc/2.25.0/org/apache/beam/sdk/transforms/Flatten.Iterables.html> >>>>>>>> is: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Input: PCollection<Iterable<T> >>>>>>>> >>>>>>>> Output: PCollection<T> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> The input/output for a explode transform would look like this: >>>>>>>> >>>>>>>> Input: PCollection<Row> The row schema has a field which is an >>>>>>>> array of T >>>>>>>> >>>>>>>> Output: PCollection<Row> The array type field from input schema is >>>>>>>> replaced with a new field of type T. The elements from the array type >>>>>>>> field >>>>>>>> are flattened into multiple rows in the new table (other fields of >>>>>>>> input >>>>>>>> table are just duplicated. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Hope this clarification helps! >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> *From: *Kyle Weaver <kcwea...@google.com> >>>>>>>> *Reply-To: *"user@beam.apache.org" <user@beam.apache.org> >>>>>>>> *Date: *Tuesday, January 12, 2021 at 4:58 PM >>>>>>>> *To: *"user@beam.apache.org" <user@beam.apache.org> >>>>>>>> *Cc: *Reuven Lax <re...@google.com> >>>>>>>> *Subject: *Re: Is there an array explode function/transform? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> @Reuven Lax <re...@google.com> yes I am aware of that transform, >>>>>>>> but that’s different from the explode operation I was referring to: >>>>>>>> https://spark.apache.org/docs/latest/api/sql/index.html#explode >>>>>>>> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspark.apache.org%2Fdocs%2Flatest%2Fapi%2Fsql%2Findex.html%23explode&data=04%7C01%7Ctaol%40zillow.com%7C1226a5d9efee43fc7d5508d8b75e5bfd%7C033464830d1840e7a5883784ac50e16f%7C0%7C0%7C637460963191408293%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=IjXWhmHTGsbpgbxa1gJ5LcOFI%2BoiGIDYBwXPnukQfxk%3D&reserved=0> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> How is it different? It'd help if you could provide the signature >>>>>>>> (input and output PCollection types) of the transform you have in mind. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Tue, Jan 12, 2021 at 4:49 PM Tao Li <t...@zillow.com> wrote: >>>>>>>> >>>>>>>> @Reuven Lax <re...@google.com> yes I am aware of that transform, >>>>>>>> but that’s different from the explode operation I was referring to: >>>>>>>> https://spark.apache.org/docs/latest/api/sql/index.html#explode >>>>>>>> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspark.apache.org%2Fdocs%2Flatest%2Fapi%2Fsql%2Findex.html%23explode&data=04%7C01%7Ctaol%40zillow.com%7C1226a5d9efee43fc7d5508d8b75e5bfd%7C033464830d1840e7a5883784ac50e16f%7C0%7C0%7C637460963191418249%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=XuUUmNB3fgBasjDj0Dq1Z2g6%2Bc5fbvluf%2BnAp2m8cuE%3D&reserved=0> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> *From: *Reuven Lax <re...@google.com> >>>>>>>> *Reply-To: *"user@beam.apache.org" <user@beam.apache.org> >>>>>>>> *Date: *Tuesday, January 12, 2021 at 2:04 PM >>>>>>>> *To: *user <user@beam.apache.org> >>>>>>>> *Subject: *Re: Is there an array explode function/transform? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Have you tried Flatten.iterables >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Tue, Jan 12, 2021, 2:02 PM Tao Li <t...@zillow.com> wrote: >>>>>>>> >>>>>>>> Hi community, >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Is there a beam function to explode an array (similarly to spark >>>>>>>> sql’s explode())? I did some research but did not find anything. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> BTW I think we can potentially use FlatMap to implement the explode >>>>>>>> functionality, but a Beam provided function would be very handy. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Thanks a lot! >>>>>>>> >>>>>>>>
