Hi Daniele, It's a good idea to implement a UDF[1] by referring to the ArrayAggFunction[2] in Flink.
I don't understand what "I don't get how RowData comes into play" means. Could you clarify it? Best, Jiabao [1] https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/functions/udfs/#aggregate-functions [2] https://github.com/apache/flink/blob/28ae3ae65d13b98dc28b919ef75c14780c512618/flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/aggregate/ArrayAggFunction.java On 2024/10/24 08:34:32 Daniele Parmeggiani wrote: > Hi Hanyu Zheng 👋 > > I've actually included the function into a UDF jar, hoping I could get > away with not forking Flink itself. > Do you think that'll work? > > In my SQL script I import the function like this: > ```sql > create temporary function ArrayAggFunction >   as 'eu.spaziodati.cp.flink.funcs.ArrayAggFunction' >   using jar '<file:///opt/flink/plugins/cp-funcs.jar';> > ``` > > Then I use it like this: > ```sql > select `...`, ArrayAggFunction(row(...)) > ``` > > So the fact that a Row is being passed into the function does not > surprise me, but I don't get how RowData comes into play. > > > Daniele > > > > On October 24, 2024, user <user@flink.apache.org> wrote: > > Hi Daniele Parmeggiani, > > > > I have some ideas regarding the issue. From the exception: > > > > java.lang.ClassCastException: class org.apache.flink.types.Row cannot > > be cast to class org.apache.flink.table.data.RowData > > This error clearly indicates that the code is trying to cast a Row > > object to a RowData object, which suggests that the input data being > > processed is of type Row. However, the backported ARRAY_AGG function > > expects RowData. The type mismatch between Row and RowData might be > > causing the error. > > > > We need to confirm whether the data type passed to ARRAY_AGG is the > > correct one. Additionally, the input and output strategy should be > > defined in BuiltInFunctionDefinitions — we should first define the > > input and output types and then let the function use them. > > > > It’s possible that checking the type in the wrong place and passing an > > incorrect data type is leading to this issue. > > > > > > -- > > > > <https://www.confluent.io> > > Hanyu (Peter) Zheng he/him/hisSoftware Engineer+1 (213) 431-7193 > > <tel:+1+(213)+431-7193> > > Follow us: > > <https://www.confluent.io/blog?utm_source=footer&utm_medium=email&utm_campaign=ch.email- > > signature_type.community_content.blog> > > <https://twitter.com/ConfluentInc> <https://www.linkedin.com/in/hanyu- > > peter-zheng/> <https://slackpass.io/confluentcommunity> > > <https://youtube.com/confluent> > > <https://www.confluent.io/get-started?utm_campaign=tm.fm- > > apac_cd.inbound&utm_source=gmail&utm_medium=organic> > > > > >
