SNOW-1657459 Improved dtype results for TIMESTAMP_LTZ type to show co…

…rrect timezone (#2328)

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   Fixes SNOW-1657459

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make sure dtype for timestamp_ltz is correct.

CHANGELOG.md

@@ -14,6 +14,7 @@
 
 - Improved `to_pandas` to persist the original timezone offset for TIMESTAMP_TZ type.
 - Improved `dtype` results for TIMESTAMP_TZ type to show correct timezone offset.
+- Improved `dtype` results for TIMESTAMP_LTZ type to show correct timezone.
 - Improved error message when passing non-bool value to `numeric_only` for groupby aggregations.
 - Removed unnecessary warning about sort algorithm in `sort_values`.
 

src/snowflake/snowpark/modin/plugin/_internal/frame.py

@@ -1489,5 +1489,14 @@ def get_datetime64tz_from_timestamp_tz(
             timestamp_tz_snowfalke_quoted_identifier,
         )
 
+    def get_datetime64tz_from_timestamp_ltz(self) -> DatetimeTZDtype:
+        """
+        Get DatetimeTZDtype for TIMESTAMP_LTZ by reading the session local timezone.
+        """
+        tz = self.ordered_dataframe.session._conn._get_client_side_session_parameter(
+            "TIMEZONE", default_value="UTC"
+        )
+        return DatetimeTZDtype(tz=tz)
+
     # END: Internal Frame mutation APIs.
     ###########################################################################

src/snowflake/snowpark/modin/plugin/compiler/snowflake_query_compiler.py

@@ -496,6 +496,8 @@ def _get_dtypes(
         return [
             self._modin_frame.get_datetime64tz_from_timestamp_tz(i)
             if t == TimestampType(TimestampTimeZone.TZ)
+            else self._modin_frame.get_datetime64tz_from_timestamp_ltz()
+            if t == TimestampType(TimestampTimeZone.LTZ)
             else TypeMapper.to_pandas(t)
             for i, t in type_map.items()
         ]

tests/integ/modin/test_dtype_mapping.py

@@ -265,7 +265,7 @@
         (
             "timestamp_ltz timestamp_ltz",
             "values ('2023-01-01 00:00:01.001'), ('2023-12-31 23:59:59.999')",
-            dtype("<M8[ns]"),
+            "datetime64[ns, America/Los_Angeles]",
             "datetime64[ns, America/Los_Angeles]",
             native_pd.DataFrame(
                 [