[CALCITE-4872] UNKNOWN SqlTypeName erroneously treated as NULL

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.30.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Will Noble
• Reporter: Will Noble
• Created: 02/Nov/21 15:28
• Updated: 19/Mar/22 09:20
• Resolved: 09/Feb/22 21:48

Description

Call createWithNullability on an UnknownSqlType currently returns a NULL type. Furthermore, it's impossible to cast to unknown types, according to SqlTypeUtil.canCastFrom. This introduces a new SqlTypeName – UNKNOWN – which behaves like NULL in all ways except that it's no longer actually equal to NULL, and can always be cast to.

Issue Links

• causes: CALCITE-5040 SqlTypeFactoryTest.testUnknownCreateWithNullabilityTypeConsistency fails
• is related to: CALCITE-4918 Add a VARIANT data type
• links to: GitHub Pull Request #2595