Cannot plan druid sql query if String Function is used

Hi,

when I try to run query which has String function (like LOWER or UPPER), I got error:

{

“error”: “Unknown exception”,

“errorMessage”: “Cannot build plan for query: SELECT lower(productname), COUNT(*) AS “Count” FROM product_view WHERE __time >= CURRENT_TIMESTAMP - INTERVAL ‘1’ DAY GROUP BY productname ORDER BY “Count” DESC”,

“errorClass”: “io.druid.java.util.common.ISE”,

“host”: null

}

my query is:

SELECT lower(productname), COUNT(*) AS “Count”

FROM product_view

WHERE __time >= CURRENT_TIMESTAMP - INTERVAL ‘1’ DAY

GROUP BY productname

ORDER BY “Count” DESC

does druid support these String Function?

my reference: https://docs.imply.io/cloud/sql#string-functions

Thank you