Cannot run `tumble(ext_stream, 1d)` on external stream, DB::Exception: This input format is only suitable for streams with a single column of type String but the number of columns is 3. (BAD_ARGUMENTS)

[jovezhong]

Describe what's wrong

Use case, I want to check the number of messages every day in the Kafka topic. I created an external stream for the topic, then want to run the tumble window with time rewind

SELECT window_start, count() FROM tumble(ext_stream,1d) where _tp_time>earliest_ts() group by window_start

Got error

Received exception from server (version 1.5.4): Code: 36. DB::Exception: Received from localhost:8463. DB::Exception: This input format is only suitable for streams with a single column of type String but the number of columns is 3. (BAD_ARGUMENTS)

Using the virtual column in the tumble window has the same error

SELECT window_start, count() FROM tumble(ext_stream,_tp_time,1d) where _tp_time>earliest_ts() group by window_start

One workaround is to create a subquery

with cte as (select _tp_time,raw from ext_stream settings seek_to='earliest')
                SELECT window_start, count() FROM tumble(cte,1d) group by window_start

But this is anti-intuition.

The issue for the error message

• What is "This input format"? Why applying tumble function will create a input format?
• "a single column of type String", should be string, not String
• "only suitable for streams with a single column of type String but the number of columns is 3" I think the message swapped the object. Could be the opposite: "This input format is only suitable for streams with the number of columns is 3 but we got a single column of type String"

This can be reproduced in latest Proton 1.5.4.

[chenziliang]

@zliang-min may you hep take a look ? Thanks

[chenziliang]

@jovezhong could you show create to share the stream definition ?

[jovezhong]

I shared the DDL on our slack, since it contains sensitive info, such as password. Any local Kafka should work too

[jovezhong]

(Jove Github Bot) assuming it is not done, deferred this ticket to the next sprint.