$columns support multiple columns

[wych42]

The doc has shown an example of $columns:

$columns(OSName, count(*) c) FROM requests

Sometimes, I need to group multi columns to find out differences, such as OS platform and version, I 'm wondering if this usage could be supported:

$columns(key_1, key_2, value) or $columns((key_1, key_2), value)

which query values as array of [key, value], where key will be used as label, and key is a combination of key_1 key_2.

[hagen1778]

Hi @marlowew
Currently, plugin doesn't support multiple labels or any mechanism to choose between them like it's done in Prometheus datasource.
But you can do it in different way:

$columns(
    concat(toString(Environment), '-', OSName) l,
    count(*) c)
FROM $table
ANY INNER JOIN oses USING  OS

here OSName is querying from separate table oses

So, in the query above you asking ClickHouse to combine your labels and you can choose any combination form you want.

[wych42]

The concat way do solve the problem. Thanks.