If you go (in chrome) to ... "more tools" "developer tools", then the network tab, you can see the SQL payloads. Here's the payload for the datasources tab:

SELECT datasource, COUNT(*) FILTER (WHERE is_active = 1) AS num_segments, COUNT(*) FILTER (WHERE is_published = 1 AND is_overshadowed = 0 AND replication_factor = 0) AS num_zero_replica_segments, COUNT(*) FILTER (WHERE is_published = 1 AND is_overshadowed = 0 AND is_available = 0 AND replication_factor > 0) AS num_segments_to_load, COUNT(*) FILTER (WHERE is_available = 1 AND is_active = 0) AS num_segments_to_drop, SUM("size") FILTER (WHERE is_active = 1) AS total_data_size, MIN("num_rows") FILTER (WHERE is_available = 1 AND is_realtime = 0) AS min_segment_rows, AVG("num_rows") FILTER (WHERE is_available = 1 AND is_realtime = 0) AS avg_segment_rows, MAX("num_rows") FILTER (WHERE is_available = 1 AND is_realtime = 0) AS max_segment_rows, SUM("num_rows") FILTER (WHERE is_active = 1) AS total_rows, CASE WHEN SUM("num_rows") FILTER (WHERE is_available = 1) <> 0 THEN (SUM("size") FILTER (WHERE is_available = 1) / SUM("num_rows") FILTER (WHERE is_available = 1)) ELSE 0 END AS avg_row_size, SUM("size" * "num_replicas") FILTER (WHERE is_active = 1) AS replicated_size FROM sys.segments GROUP BY 1 ORDER BY 1

(That was on a recent druid version. Older versions may be different. You can check the SQL payload to find out. Or run the above query to see the results.)