bug: bad comparsion between extension types

vortex-array/src/arrays/extension/compute/compare.rs

@@ -48,3 +48,107 @@ impl CompareKernel for Extension {
         Ok(None)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Arc;
+
+    use vortex_buffer::buffer;
+    use vortex_error::VortexResult;
+
+    use crate::Canonical;
+    use crate::IntoArray;
+    use crate::LEGACY_SESSION;
+    use crate::VortexSessionExecute;
+    use crate::arrays::BoolArray;
+    use crate::arrays::ExtensionArray;
+    use crate::arrays::datetime::TemporalArray;
+    use crate::assert_arrays_eq;
+    use crate::builtins::ArrayBuiltins;
+    use crate::dtype::Nullability;
+    use crate::extension::datetime::Date;
+    use crate::extension::datetime::TimeUnit;
+    use crate::scalar_fn::fns::operators::Operator;
+
+    /// Timestamps store UTC instants regardless of timezone (Arrow semantics).
+    /// The raw i64 is always relative to epoch, timezone is display metadata.
+    /// Same raw values + same time unit = same instant, so result should be all-true.
+    #[test]
+    fn compare_timestamps_different_timezones() -> VortexResult<()> {
+        let values = buffer![1_000_000i64, 2_000_000, 3_000_000].into_array();
+
+        let ts_utc =
+            TemporalArray::new_timestamp(values.clone(), TimeUnit::Seconds, Some(Arc::from("UTC")))
+                .into_array();
+
+        let ts_ny = TemporalArray::new_timestamp(
+            values,
+            TimeUnit::Seconds,
+            Some(Arc::from("America/New_York")),
+        )
+        .into_array();
+
+        let mut ctx = LEGACY_SESSION.create_execution_ctx();
+
+        let result = ts_utc
+            .binary(ts_ny, Operator::Eq)?
+            .execute::<Canonical>(&mut ctx)?
+            .into_array();
+
+        assert_arrays_eq!(result, BoolArray::from_iter([true, true, true]));
+
+        Ok(())
+    }
+
+    /// BUG: Comparing Timestamp(seconds) vs Date(milliseconds) — different extension
+    /// type IDs — should yield all-false (or error), but the kernel silently compares
+    /// raw i64 storage and returns all-true.
+    #[test]
+    fn compare_timestamp_vs_date() -> VortexResult<()> {
+        let ts_values = buffer![86_400i64, 172_800, 259_200].into_array();
+        let ts_array =
+            TemporalArray::new_timestamp(ts_values, TimeUnit::Seconds, None).into_array();
+
+        let date_values = buffer![86_400i64, 172_800, 259_200].into_array();
+        let date_ext_dtype = Date::new(TimeUnit::Milliseconds, Nullability::NonNullable).erased();
+        let date_array = ExtensionArray::new(date_ext_dtype, date_values).into_array();
+
+        let mut ctx = LEGACY_SESSION.create_execution_ctx();
+
+        let result = ts_array
+            .binary(date_array, Operator::Eq)?
+            .execute::<Canonical>(&mut ctx)?
+            .into_array();
+
+        // Different extension types should never be equal.
+        assert_arrays_eq!(result, BoolArray::from_iter([false, false, false]));
+
+        Ok(())
+    }
+
+    /// BUG: Comparing Timestamp(milliseconds) vs Timestamp(seconds) — same extension
+    /// type ID but different metadata — should yield all-false (or error), but the
+    /// kernel silently compares raw i64 storage. 1000ms != 1000s.
+    #[test]
+    fn compare_timestamps_different_units() -> VortexResult<()> {
+        let millis = buffer![1000i64, 2000, 3000].into_array();
+        let seconds = buffer![1000i64, 2000, 3000].into_array();
+
+        let ts_millis =
+            TemporalArray::new_timestamp(millis, TimeUnit::Milliseconds, None).into_array();
+        let ts_seconds =
+            TemporalArray::new_timestamp(seconds, TimeUnit::Seconds, None).into_array();
+
+        let mut ctx = LEGACY_SESSION.create_execution_ctx();
+
+        let result = ts_millis
+            .binary(ts_seconds, Operator::Eq)?
+            .execute::<Canonical>(&mut ctx)?
+            .into_array();
+
+        // 1000ms != 1000s, should be all-false.
+        assert_arrays_eq!(result, BoolArray::from_iter([false, false, false]));
+
+        Ok(())
+    }
+}