Union Query with Join throws error

[pjain1]

Have been trying to use a right join query with unioned datasource to achieve sort of null filling since timeseries have limited support for returning empty buckets (like it just fills missing buckets within segment's actual min and max time not the query min and max times) but it fails.

Affected Version

29.0.1

Description

SELECT "t2"."hour", "t1"."Count" FROM (
  (SELECT TIME_FLOOR("__time", 'PT1H') AS "hour",
    COUNT(*) AS "Count"
    FROM "inline_data_day" GROUP BY 1) "t1"
  RIGHT JOIN (
    SELECT CAST('2023-10-10T00:00:00.000Z' as TIMESTAMP) as "hour"
    UNION ALL 
    SELECT CAST('2023-10-10T01:00:00.000Z' AS TIMESTAMP) as "hour"
    UNION ALL 
    SELECT CAST('2023-10-10T02:00:00.000Z' AS TIMESTAMP) as "hour"
  ) "t2" 
  ON "t1"."hour"="t2"."hour"
)

This fails with

Query could not be planned. A possible reason is [SQL requires union with input of a datasource type that is not supported. Union operation is only supported between regular tables. ]

inline_data_day is just

__time	                        v	count
2023-10-10T00:00:00.000Z	a	1
2023-10-10T02:00:00.000Z	b	2
2023-10-11T00:00:00.000Z	a	1
2023-10-11T02:00:00.000Z	b	2