BUG: fixed OutOfBoundsDatetime exception when errors=coerce #45319 (#47794)

* BUG: fixed OutOfBoundsDatetime exception when errors=coerce #45319

* BUG: Added test and release note #45319

* BUG: Restructured test parameters #45319

* BUG: Restructured test #45319

* BUG: Restructured parameters for test #45319

* BUG: Renamed test and added raise and ignore cases #45319

* BUG: Changed exception case #45319

Co-authored-by: Steven Rotondo <[email protected]>

Author: srotondo

doc/source/whatsnew/v1.5.0.rst

@@ -900,6 +900,7 @@ Datetimelike
 - Bug in :meth:`DatetimeIndex.resolution` incorrectly returning "day" instead of "nanosecond" for nanosecond-resolution indexes (:issue:`46903`)
 - Bug in :class:`Timestamp` with an integer or float value and ``unit="Y"`` or ``unit="M"`` giving slightly-wrong results (:issue:`47266`)
 - Bug in :class:`.DatetimeArray` construction when passed another :class:`.DatetimeArray` and ``freq=None`` incorrectly inferring the freq from the given array (:issue:`47296`)
+- Bug in :func:`to_datetime` where ``OutOfBoundsDatetime`` would be thrown even if ``errors=coerce`` if there were more than 50 rows (:issue:`45319`)
 - Bug when adding a :class:`DateOffset` to a :class:`Series` would not add the ``nanoseconds`` field (:issue:`47856`)
 -
 

pandas/core/tools/datetimes.py

@@ -228,7 +228,11 @@ def _maybe_cache(
         unique_dates = unique(arg)
         if len(unique_dates) < len(arg):
             cache_dates = convert_listlike(unique_dates, format)
-            cache_array = Series(cache_dates, index=unique_dates)
+            # GH#45319
+            try:
+                cache_array = Series(cache_dates, index=unique_dates)
+            except OutOfBoundsDatetime:
+                return cache_array
             # GH#39882 and GH#35888 in case of None and NaT we get duplicates
             if not cache_array.index.is_unique:
                 cache_array = cache_array[~cache_array.index.duplicated()]

pandas/tests/tools/test_to_datetime.py

@@ -2777,3 +2777,34 @@ def test_to_datetime_monotonic_increasing_index(cache):
     result = to_datetime(times.iloc[:, 0], cache=cache)
     expected = times.iloc[:, 0]
     tm.assert_series_equal(result, expected)
+
+
+@pytest.mark.parametrize(
+    "series_length",
+    [40, start_caching_at, (start_caching_at + 1), (start_caching_at + 5)],
+)
+def test_to_datetime_cache_coerce_50_lines_outofbounds(series_length):
+    # GH#45319
+    s = Series(
+        [datetime.fromisoformat("1446-04-12 00:00:00+00:00")]
+        + ([datetime.fromisoformat("1991-10-20 00:00:00+00:00")] * series_length)
+    )
+    result1 = to_datetime(s, errors="coerce", utc=True)
+
+    expected1 = Series(
+        [NaT] + ([Timestamp("1991-10-20 00:00:00+00:00")] * series_length)
+    )
+
+    tm.assert_series_equal(result1, expected1)
+
+    result2 = to_datetime(s, errors="ignore", utc=True)
+
+    expected2 = Series(
+        [datetime.fromisoformat("1446-04-12 00:00:00+00:00")]
+        + ([datetime.fromisoformat("1991-10-20 00:00:00+00:00")] * series_length)
+    )
+
+    tm.assert_series_equal(result2, expected2)
+
+    with pytest.raises(OutOfBoundsDatetime, match="Out of bounds nanosecond timestamp"):
+        to_datetime(s, errors="raise", utc=True)