[CALCITE-4467] Incorrect simplification for 'NaN' value

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Fix Version/s: 1.27.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Jesús Camacho Rodríguez
• Reporter: Jesús Camacho Rodríguez
• Created: 14/Jan/21 04:27
• Updated: 27/Feb/24 22:23
• Resolved: 16/Feb/21 04:12

Description

RexSimplify simplifies x = x to null or x is not null (similarly <= and >=), and x != x to null and x is null (similarly < and >).
https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L363

This may not be applicable in some cases. For instance, if the type of x is floating-point, x could be 'NaN'. While some RDBMS consider 'NaN' = 'NaN' (e.g., Postgres), some others consider 'NaN' != 'NaN' following the IEEE 754 standard. For the latest, the rewriting above will result in incorrect results.

I think we should simply ignore this simplification for floating-point type.

Issue Links

• links to: GitHub Pull Request #2327