Aggregation without windows

[laysakura]

Is your feature request related to a problem? Please describe.

Lack of triggers.

Describe the solution you'd like

https://nightlies.apache.org/flink/flink-docs-release-1.15/docs/dev/table/sql/queries/group-agg/

For streaming queries, it is important to understand that Flink runs continuous queries that never terminate. Instead, they update their result table according to the updates on its input tables. For the above query, Flink will output an updated count each time a new row is inserted into the Orders table.

Describe alternatives you've considered

Additional context