[SPARK-47210] Addition of implicit casting without indeterminate support

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0
• Fix Version/s: 4.0.0
• Component/s: SQL
• Labels: pull-request-available
• Assignee: Mihailo Milosevic
• Reporter: Mihailo Milosevic
• Created: 28/Feb/24 13:48
• Updated: 03/Apr/24 23:50
• Resolved: 03/Apr/24 23:50

Description

What changes were proposed in this pull request?
This PR adds automatic casting and collations resolution as per `PGSQL` behaviour:

1. Collations set on the metadata level are implicit
2. Collations set using the `COLLATE` expression are explicit
3. When there is a combination of expressions of multiple collations the output will be:

• if there are explicit collations and all of them are equal then that collation will be the output
• if there are multiple different explicit collations `COLLATION_MISMATCH.EXPLICIT` will be thrown
• if there are no explicit collations and only a single type of non default collation, that one will be used
• if there are no explicit collations and multiple non-default implicit ones `COLLATION_MISMATCH.IMPLICIT` will be thrown

Why are the changes needed?
We need to be able to compare columns and values with different collations and set a way of explicitly changing the collation we want to use.

Issue Links

• links to: GitHub Pull Request #45383