Fix incorrect results returned by min, max and avg

[Yury-Fridlyand]

Fix incorrect results returned by min, max and avg when processing null/missing values only.

Signed-off-by: Yury-Fridlyand [email protected]

Description

Before

opensearchsql> select min(int0) from calcs where int0 IS NULL;
fetched rows / total rows = 1/1
+-------------+
| min(int0)   |
|-------------|
| 2147483647  |
+-------------+

After

opensearchsql> select min(int0) from calcs where int0 IS NULL;
fetched rows / total rows = 1/1
+-------------+
| min(int0)   |
|-------------|
| null        |
+-------------+

Fixed:

• min
• max
• avg

Not fixed:

• sum

opensearchsql> select sum(int0) from calcs where int0 IS NULL;
fetched rows / total rows = 1/1
+-------------+
| sum(int0)   |
|-------------|
| 0           |
+-------------+

mysql> select sum(int0) from calcs where int0 IS NULL;

+-----------+
| sum(int0) |
+-----------+
|      NULL |
+-----------+
1 row in set (0.00 sec)

This requires much more changes.

Not affected

• var_samp
• var_pop
• stddev_samp
• stddev_pop

Issues Resolved

opensearch-project#817

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[acarbonetto]

😆

[acarbonetto]

What the MySQL result for sum(null)? Is it supposed to be null or zero?

[acarbonetto]

you don't want to give these index numbers?

[Yury-Fridlyand]

They are assigned automatically if not given.

[acarbonetto]

is this not confusing?

[Yury-Fridlyand]

key is not a PK. Just a column.

[acarbonetto]

is "key": "null" also not confusing?

[Yury-Fridlyand]

What the MySQL result for sum(null)? Is it supposed to be null or zero?

mysql> select sum(num0) from calcs where num0 is null;
+-----------+
| sum(num0) |
+-----------+
|      NULL |
+-----------+
1 row in set (0.00 sec)

[MitchellGale]

LGTM