Hi Lei, Are you trying a regular left join query?
Non-time-based operators (e.g. regular join in your case) will emit result when input is not complete, the result will be updated when more inputs come in (by emitting upsert/retract messages). But time-based operators (e.g. windowed aggregate, interval join) can emit final result because it will wait input to be complete (by watermark), thus it can produce append-only stream. Maybe you can try to update your query to interval join [1] (called time-windowed join in docs currently) to get an append result. Best, Jark [1]: https://ci.apache.org/projects/flink/flink-docs-release-1.10/dev/table/sql/queries.html#joins On Tue, 10 Mar 2020 at 18:41, wangl...@geekplus.com.cn < wangl...@geekplus.com.cn> wrote: > Hi Jark, > Thanks for the explanation. > The group by statement will result a not append stream. > I have just tried a join statement and want to send the result to kafka, > it also has the error: > AppendStreamTableSink requires that Table has only insert changes > Why the join result is not appendable. It confused me. > > Thanks, > Lei > > > *From:* Jark Wu <imj...@gmail.com> > *Date:* 2020-03-09 19:25 > *To:* wangl...@geekplus.com.cn > *CC:* user <user@flink.apache.org> > *Subject:* Re: Kafka sink only support append mode? > Hi Lei, > > Yes. Currently, Kafka sink only supports append mode. Other update mode > (e.g. upsert mode / retract mode) is on the agenda. > For now, you can customize a KafkaTableSink with implementing > UpsertStreamTableSink interface, where you will get a Tuple2<Boolean, Row> > records, > and the Boolean represents insert or delete operation. Then you can encode > the insert/delete operation into Kafka storage or just ignore the > operations. > > Best, > Jark > > On Mon, 9 Mar 2020 at 19:14, wangl...@geekplus.com.cn < > wangl...@geekplus.com.cn> wrote: > >> I wrote a simple program reading from kafka using sql and sink to >> kafka. >> But only 'update-mode' = 'append' is supported for sink table and the >> query sql must have no group statement. >> Only append mode is supported for kafka sink? >> >> Thanks, >> Lei >> >> >>
