I have been using Druid 28.0.0 and found a new bug.
The whole-query cache for groupBy queries with multiple post-aggregation metrics is broken.
However, if there are no post-aggregation metrics or a single post-aggregation metric, this bug does not seem to occur.

This bug is probably caused by a new feature in #11595.

Affected Version

Druid 28.0.0

Description

Below is a description of what happens when the bug occurs.

Settings changed from default settings

• druid.broker.cache.useResultLevelCache=true
• druid.broker.cache.populateResultLevelCache=true

Query

SELECT
  "channel","cityName"
  ,COUNT(*) AS a1
  ,COUNT(*) * 2 AS a2
  ,COUNT(*) * 3 AS a3
FROM "wikipedia"
WHERE TIME_IN_INTERVAL("__time", '2015-09-12T00:00:00.000Z/2015-09-13T00:00:00.000Z')
GROUP BY 1,2
ORDER BY 3 DESC
LIMIT 1

No cache result

Result level cache result