[HIVE-25749] Check if RelMetadataQuery.collations() returns null to avoid NPE

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0
• Fix Version/s: 4.0.0-alpha-1
• Component/s: CBO, Query Planning
• Labels: pull-request-available
• Assignee: Alessandro Solimando
• Reporter: Alessandro Solimando
• Created: 29/Nov/21 16:30
• Updated: 17/Nov/22 08:48
• Resolved: 30/Nov/21 08:52

Description

Accoring to "RelMetadataQuery.collations()" javadoc, the method can return "null" if collactions information are not available.

Hive invokes the method in two places (RelFieldTrimmer and HiveJoin), but it does not check for "null" return values, which can cause NPE.

For RelFieldTrimmer, the same bug has been fixed in Calcite (where the code has been taken from) here: https://github.com/apache/calcite/commit/47871235177a3a0d398b1d890d1d2e947028e052

Issue Links

• links to: GitHub Pull Request #2823