Hi all!
Fabian and I worked on a FLIP for Stream Aggregations in the Table API.
You can find the FLIP-11 here:
https://cwiki.apache.org/confluence/display/FLINK/FLIP-11%3A+Table+API+Stream+Aggregations
Motivation for the FLIP:
The Table API is a declarative API to define queries on static and
streaming tables. So far, only projection, selection, and union are
supported operations on streaming tables.
This FLIP proposes to add support for different types of aggregations on
top of streaming tables. In particular, we seek to support:
- Group-window aggregates, i.e., aggregates which are computed for a
group of elements. A (time or row-count) window is required to bound the
infinite input stream into a finite group.
- Row-window aggregates, i.e., aggregates which are computed for each
row, based on a window (range) of preceding and succeeding rows.
Each type of aggregate shall be supported on keyed/grouped or
non-keyed/grouped data streams for streaming tables as well as batch tables.
We are looking forward to your feedback.
Timo
