I’m trying to utilize Calcite as a SQL query transformer on top of PostgreSQL database.
The schema is somewhat non-trivial. It’s basically a schema of user-defined entities and columns:

I am using Calcite for SQL parsing and execution. During the application startup, I have already instantiated SchemaPlus, FrameworkConfig, SqlValidator, VolcanoPlanner, and CalciteCatalogReader.

I’m seeing what appears to be a bug when translating a logical plan to a physical plan when a computed column that uses a CASE statement is referenced in a WHERE clause. The generated physical SQL is invalid, as it appears to be trying to coerce a CASE expression into a BOOLEAN. It’s unclear to me if I’m setting this up incorrectly or if this is a problem in the planner logic itself.

Using Apache Calcite, I’m trying to generate SQL Server conformant string concatenation, but the result always uses the default “||” operator. I’ve outlined what I’m trying to do below and am wondering if I’m going about this incorrectly.