Function test_nested_union_partial_overlap

src/expr/src/interpret.rs:1859–1925

()

    #[mz_ore::test]
    fn test_nested_union_partial_overlap() {
        // `Nested(map)` constrains a key only when the key is present in `map`; absent
        // keys mean "anything". So the union of two Nested specs must drop any key
        // that's missing from one side, because `x ∪ anything = anything`. Only keys
        // present in *both* sides survive (with their per-key specs unioned).
        let a = ResultSpec::map_spec(
            [
                ("x".into(), ResultSpec::value(Datum::String("a"))),
                ("y".into(), ResultSpec::value(Datum::String("b"))),
                ("c".into(), ResultSpec::value(Datum::String("c"))),
            ]
            .into_iter()
            .collect(),
        );
        let b = ResultSpec::map_spec(
            [
                ("x".into(), ResultSpec::value(Datum::String("a2"))),
                ("y".into(), ResultSpec::value(Datum::String("b2"))),
                ("z".into(), ResultSpec::value(Datum::String("z"))),
            ]
            .into_iter()
            .collect(),
        );

        let unioned = a.union(b);

        // Push the unioned spec through `->> <key>`: keys only in one side must
        // admit NULL (the other side is unconstrained, so the field could be absent
        // there); shared keys must include both observed values.
        let arena = RowArena::new();
        let relation = ReprRelationType::new(vec![ReprScalarType::Jsonb.nullable(false)]);

        // Key only in `a`: the union must admit NULL.
        {
            let mut interpreter = ColumnSpecs::new(&relation, &arena);
            interpreter.push_column(0, unioned.clone());
            let expr = MirScalarExpr::column(0).call_binary(
                MirScalarExpr::literal_ok(Datum::from("c"), ReprScalarType::String),
                JsonbGetStringStringify,
            );
            assert!(interpreter.expr(&expr).range.may_contain(Datum::Null));
        }

        // Key only in `b`: symmetric.
        {
            let mut interpreter = ColumnSpecs::new(&relation, &arena);
            interpreter.push_column(0, unioned.clone());
            let expr = MirScalarExpr::column(0).call_binary(
                MirScalarExpr::literal_ok(Datum::from("z"), ReprScalarType::String),
                JsonbGetStringStringify,
            );
            assert!(interpreter.expr(&expr).range.may_contain(Datum::Null));
        }

        // Key in both: result must include both observed values.
        {
            let mut interpreter = ColumnSpecs::new(&relation, &arena);
            interpreter.push_column(0, unioned);