[IMPALA-10132] Implement ds_hll_estimate_bounds()

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 4.0.0
• Epic Color: ghx-label-11
• Assignee: Fucun Chu
• Reporter: Adam Tamas
• Created: 02/Sep/20 13:33
• Updated: 01/Nov/20 07:30
• Resolved: 01/Nov/20 07:30

Description

In hive ds_hll_estimate_bounds() gives back an array of doubles.

An example for a sketch created from a table which contains only a single value:

(select ds_hll_estimate_bounds(ds_hll_sketch(i)) from t;)
+-------------------------------+
|              _c0              |
+-------------------------------+
| [1.0,1.0,1.0000998634873453]  |
+-------------------------------+

The values of the array is probably a lower bound, an estimate and an upper bound of the sketch.