[CALCITE-7864] RANGE window frames should handle NULL ORDER BY keys

[letian-jiang]

Jira Link

CALCITE-7864

Changes Proposed

Fix a NullPointerException when evaluating RANGE window frames with offset bounds and NULL ORDER BY keys.

Guard boundary arithmetic for nullable keys and preserve NULL as the boundary search key. Explicitly box the non-NULL result to prevent implicit unboxing in the conditional expression.

For NULL keys, offset lower and upper bounds resolve to the first and last NULL peers, respectively. UNBOUNDED endpoints retain their partition-boundary behavior.

For example:

SELECT k,
       SUM(v) OVER (
         ORDER BY k NULLS LAST
         RANGE BETWEEN 1 PRECEDING AND CURRENT ROW
       ) AS s
FROM (VALUES (1, 10), (2, 20),
             (CAST(NULL AS INTEGER), 100), (NULL, 200)) AS t(k, v)

Previously, this query threw a NullPointerException. It now returns (1, 10), (2, 30), (NULL, 300), (NULL, 300), ignoring row order.

Add 28 parameterized regression cases covering INTEGER/BIGINT, NULLS FIRST/LAST, offsets at both frame endpoints, and combinations with CURRENT ROW and UNBOUNDED bounds.

[mihaibudiu]

how did you validate these expected results?
Please add a comment explaining.

[letian-jiang]

Thanks for the review. I ran all 28 SQL cases against PostgreSQL 14.24 and confirmed that all 140 result rows match the expected results, ignoring row order while preserving duplicate NULL-key rows. I also added a comment documenting the verification method and PostgreSQL version in d6df043.

[mihaibudiu]

You can squash the commits for merging.

[letian-jiang]

Thanks for the review! I’ve squashed the commits into a single commit: c1916eb.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud