Suggest clarifying that GROUP BY and SELECT's fields should be non-overlapping

[jlebar]

In most SQL dialects that I have used, the fields in GROUP BY's must be a subset of those in SELECT'. For example SELECT foo, sum(bar) GROUP BY foo is legal, but SELECT sum(bar), GROUP BY foo is not legal.

In InfluxQL, I am understanding that it's the opposite. The sets of fields in SELECT and GROUP BY must be non-overlapping, otherwise I get err: mixing aggregate and non-aggregate queries is not supported.

I wonder if

a) The documentation could be explicit about this difference between InfluxQL and most other SQLs.

b) The error message could be improved?

URL for relevant page?

https://docs.influxdata.com/influxdb/v1.7/query_language/data_exploration/#the-group-by-clause

What products and version are you using?

InfluxDB 1.7

Where did you look before opening the issue?

I eventually found it in the docs, but it took me a while to figure it out...

[kelseiv]

Thank you, @jlebar!

Updated docs to be more explicit about the following:

• cannot GROUP BY fields
• SELECT cannot include an aggregate function with any of the following:
  • non-aggregate/selector function
  • tag key
  • field key

In your example, including both an aggregate and non-aggregate value in the SELECT clause was the issue—you can overlap SELECT tags and GROUP BY tags.

I agree, the error message could be more explicit:
SELECT clause cannot include an aggregate function and a non-aggregate function, field key, or tag key.

PS. Error messages are updated in another repo—I’ll create an associated issue and link here so you know where it lands.

[kelseiv]

https://github.com/influxdata/docs.influxdata.com/pull/2672/files

[kelseiv]

@jlebar associated issue can be tracked here: influxdata/influxdb#18764

Thank you for reporting!