Function plan_builder_unnest

datafusion/expr/src/logical_plan/builder.rs:2629–2765

()

    #[test]
    fn plan_builder_unnest() -> Result<()> {
        // Cannot unnest on a scalar column
        let err = nested_table_scan("test_table")?
            .unnest_column("scalar")
            .unwrap_err();

        let DataFusionError::Internal(desc) = err else {
            return plan_err!("Plan should have returned an DataFusionError::Internal");
        };

        let desc = (*desc
            .split(DataFusionError::BACK_TRACE_SEP)
            .collect::<Vec<&str>>()
            .first()
            .unwrap_or(&""))
        .to_string();

        assert_snapshot!(desc, @"trying to unnest on invalid data type UInt32");

        // Unnesting the strings list.
        let plan = nested_table_scan("test_table")?
            .unnest_column("strings")?
            .build()?;

        assert_snapshot!(plan, @r"
        Unnest: lists[test_table.strings|depth=1] structs[]
          TableScan: test_table
        ");

        // Check unnested field is a scalar
        let field = plan.schema().field_with_name(None, "strings").unwrap();
        assert_eq!(&DataType::Utf8, field.data_type());

        // Unnesting the singular struct column result into 2 new columns for each subfield
        let plan = nested_table_scan("test_table")?
            .unnest_column("struct_singular")?
            .build()?;

        assert_snapshot!(plan, @r"
        Unnest: lists[] structs[test_table.struct_singular]
          TableScan: test_table
        ");

        for field_name in &["a", "b"] {
            // Check unnested struct field is a scalar
            let field = plan
                .schema()
                .field_with_name(None, &format!("struct_singular.{field_name}"))
                .unwrap();
            assert_eq!(&DataType::UInt32, field.data_type());
        }

        // Unnesting multiple fields in separate plans
        let plan = nested_table_scan("test_table")?
            .unnest_column("strings")?
            .unnest_column("structs")?
            .unnest_column("struct_singular")?
            .build()?;