[CALCITE-4195] Cast between types with different collators must be evaluated as not monotonic

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.24.0
• Fix Version/s: 1.26.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Ruben Q L
• Reporter: Ruben Q L
• Created: 26/Aug/20 14:05
• Updated: 08/Feb/22 12:07
• Resolved: 28/Aug/20 07:17

Description

Problem related to the feature CALCITE-3951.

A cast operation from a character type to another character type that has a different collator must be evaluated as not monotonic. Currently this is not the case.
This has an impact e.g. in SortProjectTransposeRule, since we can incorrectly transpose a sort after a projection than contains such a cast, and we end up with a plan that will return a different result than the original one (it is not the same casting and then sorting; than sorting and then casting).

Issue Links

• is caused by: CALCITE-3951 Support different string comparison based on SqlCollation
• is related to: CALCITE-5003 MergeUnion on types with different collators produces wrong result
• links to: GitHub Pull Request #2122