sam lin created FLINK-19196:
-------------------------------
Summary: FlinkSQL aggregation function to aggregate array typed
column to Map/Multiset
Key: FLINK-19196
URL: https://issues.apache.org/jira/browse/FLINK-19196
Project: Flink
Issue Type: New Feature
Components: Table SQL / API
Affects Versions: 1.11.1
Reporter: sam lin
Hi,
For FlinkSQL, how do I aggregate an array typed column to a Map/Multiset type?
e.g. Given the source events:
userID, arr_types
1, [a, b]
2, [a]
1, [b, c]
```
SELECT userID, collect_arr(arr_types) FROM src_table GROUP BY userID
```
Using the above SQL could produce results like:
1, \{a: 1, b: 2, c:1}
2, \{a: 1}
My question is do we have existing UDF to do that? If not, what is the
recommended way to achieve this? I'm happy to write a UDF if you could provide
some code pointers. Thanks in advance!
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