Windowing query fails when wrapped in an outer select

[jhbruhn]

The following windowing query, which is supposed to calculate the derivative of an increasing counter, fails with this error:

Error: RUNTIME_FAILURE (OPERATOR)
Not enough capacity for even one row! Need[26] but have[0].
org.apache.druid.java.util.common.IAE

SELECT AVG("power_kw") AS "AVG(power_kw)"
FROM
  (SELECT (now_time) as "__time",
          (now_value - previous_value) / ((TIMESTAMP_TO_MILLIS("now_time") - TIMESTAMP_TO_MILLIS("previous_time")) / (60.0 * 60.0 * 1000.0)) as "power_kw"
   FROM
     (SELECT __time as "now_time",
             LAG("positive_active_energy_total_kwh") over w as previous_value,
                                                          LAG("__time") over w as previous_time,
                                                                             "positive_active_energy_total_kwh" as now_value
      FROM "offis.meter.electricity"
      GROUP BY __time,
               id,
               "positive_active_energy_total_kwh" WINDOW w AS (PARTITION BY id
                                                               ORDER BY (__time) DESC)
      ORDER BY "now_time" DESC)
   WHERE "now_value" IS NOT NULL) AS "virtual_table"

Affected Version

29.0.0

Description

The cluster consists of a simple k8s single node configuration as provided by the Druid K8s Operator. The data is a time series of an electricity meter, so the only table needed for this to work is one with a "__time" column and a positive_active_energy_total_kwh-double.

The inner two SELECTs work as a standalone query, but when wrapped in the outer SELECT (which is generated by Apache Superset), the query fails with the beforementioned error.

The log only contains the error-message.