Add checks & testcase where min/max stats can be null, if the column …

…is empty

python/cudf/cudf/io/orc.py

@@ -41,43 +41,90 @@ def _parse_column_statistics(cs, column_statistics_blob):
         column_statistics["number_of_values"] = cs.numberOfValues
     if cs.HasField("hasNull"):
         column_statistics["has_null"] = cs.hasNull
+
     if cs.HasField("intStatistics"):
-        column_statistics["minimum"] = cs.intStatistics.minimum
-        column_statistics["maximum"] = cs.intStatistics.maximum
+        column_statistics["minimum"] = (
+            cs.intStatistics.minimum
+            if cs.intStatistics.HasField("minimum")
+            else None
+        )
+        column_statistics["maximum"] = (
+            cs.intStatistics.maximum
+            if cs.intStatistics.HasField("maximum")
+            else None
+        )
         column_statistics["sum"] = (
             cs.intStatistics.sum if cs.intStatistics.HasField("sum") else None
         )
+
     elif cs.HasField("doubleStatistics"):
-        column_statistics["minimum"] = cs.doubleStatistics.minimum
-        column_statistics["maximum"] = cs.doubleStatistics.maximum
+        column_statistics["minimum"] = (
+            cs.doubleStatistics.minimum
+            if cs.doubleStatistics.HasField("minimum")
+            else None
+        )
+        column_statistics["maximum"] = (
+            cs.doubleStatistics.maximum
+            if cs.doubleStatistics.HasField("maximum")
+            else None
+        )
         column_statistics["sum"] = (
             cs.doubleStatistics.sum
             if cs.doubleStatistics.HasField("sum")
             else None
         )
+
     elif cs.HasField("stringStatistics"):
-        column_statistics["minimum"] = cs.stringStatistics.minimum
-        column_statistics["maximum"] = cs.stringStatistics.maximum
+        column_statistics["minimum"] = (
+            cs.stringStatistics.minimum
+            if cs.stringStatistics.HasField("minimum")
+            else None
+        )
+        column_statistics["maximum"] = (
+            cs.stringStatistics.maximum
+            if cs.stringStatistics.HasField("maximum")
+            else None
+        )
         column_statistics["sum"] = cs.stringStatistics.sum
+
     elif cs.HasField("bucketStatistics"):
         column_statistics["true_count"] = cs.bucketStatistics.count[0]
         column_statistics["false_count"] = (
             column_statistics["number_of_values"]
             - column_statistics["true_count"]
         )
+
     elif cs.HasField("decimalStatistics"):
-        column_statistics["minimum"] = cs.decimalStatistics.minimum
-        column_statistics["maximum"] = cs.decimalStatistics.maximum
+        column_statistics["minimum"] = (
+            cs.decimalStatistics.minimum
+            if cs.decimalStatistics.HasField("minimum")
+            else None
+        )
+        column_statistics["maximum"] = (
+            cs.decimalStatistics.maximum
+            if cs.decimalStatistics.HasField("maximum")
+            else None
+        )
         column_statistics["sum"] = cs.decimalStatistics.sum
+
     elif cs.HasField("dateStatistics"):
-        column_statistics["minimum"] = datetime.datetime.fromtimestamp(
-            datetime.timedelta(cs.dateStatistics.minimum).total_seconds(),
-            datetime.timezone.utc,
+        column_statistics["minimum"] = (
+            datetime.datetime.fromtimestamp(
+                datetime.timedelta(cs.dateStatistics.minimum).total_seconds(),
+                datetime.timezone.utc,
+            )
+            if cs.dateStatistics.HasField("minimum")
+            else None
         )
-        column_statistics["maximum"] = datetime.datetime.fromtimestamp(
-            datetime.timedelta(cs.dateStatistics.maximum).total_seconds(),
-            datetime.timezone.utc,
+        column_statistics["maximum"] = (
+            datetime.datetime.fromtimestamp(
+                datetime.timedelta(cs.dateStatistics.maximum).total_seconds(),
+                datetime.timezone.utc,
+            )
+            if cs.dateStatistics.HasField("maximum")
+            else None
         )
+
     elif cs.HasField("timestampStatistics"):
         # Before ORC-135, the local timezone offset was included and they were
         # stored as minimum and maximum. After ORC-135, the timestamp is
@@ -93,6 +140,7 @@ def _parse_column_statistics(cs, column_statistics_blob):
             column_statistics["maximum"] = datetime.datetime.fromtimestamp(
                 cs.timestampStatistics.maximumUtc / 1000, datetime.timezone.utc
             )
+
     elif cs.HasField("binaryStatistics"):
         column_statistics["sum"] = cs.binaryStatistics.sum
 

python/cudf/cudf/tests/test_orc.py

@@ -5,6 +5,7 @@
 import os
 import random
 from io import BytesIO
+from string import ascii_lowercase
 
 import numpy as np
 import pandas as pd
@@ -1217,10 +1218,59 @@ def test_statistics_sum_overflow():
         writer.write((1, -1, 1))
 
     file_stats, stripe_stats = cudf.io.orc.read_orc_statistics([buff])
-    assert file_stats[0]["a"]["sum"] is None
-    assert file_stats[0]["b"]["sum"] is None
-    assert file_stats[0]["c"]["sum"] == minint64 + 1
+    assert file_stats[0]["a"].get("sum") is None
+    assert file_stats[0]["b"].get("sum") is None
+    assert file_stats[0]["c"].get("sum") == minint64 + 1
 
-    assert stripe_stats[0]["a"]["sum"] is None
-    assert stripe_stats[0]["b"]["sum"] is None
-    assert stripe_stats[0]["c"]["sum"] == minint64 + 1
+    assert stripe_stats[0]["a"].get("sum") is None
+    assert stripe_stats[0]["b"].get("sum") is None
+    assert stripe_stats[0]["c"].get("sum") == minint64 + 1
+
+
+def test_empty_statistics():
+    buff = BytesIO()
+    orc_schema = po.Struct(
+        a=po.BigInt(),
+        b=po.Double(),
+        c=po.String(),
+        d=po.Decimal(11, 2),
+        e=po.Date(),
+        f=po.Timestamp(),
+        g=po.Boolean(),
+        h=po.Binary(),
+        i=po.BigInt(),
+        # One column with non null value, else cudf/pyorc readers crash
+    )
+    data = tuple([None] * (len(orc_schema.fields) - 1) + [1])
+    with po.Writer(buff, orc_schema) as writer:
+        writer.write(data)
+
+    got = cudf.io.orc.read_orc_statistics([buff])
+
+    # Check for both file and stripe stats
+    for stats in got:
+        # Similar expected stats for the first 6 columns in this case
+        for col_name in ascii_lowercase[:6]:
+            assert stats[0][col_name].get("number_of_values") == 0
+            assert stats[0][col_name].get("has_null") is True
+            assert stats[0][col_name].get("minimum") is None
+            assert stats[0][col_name].get("maximum") is None
+        for col_name in ascii_lowercase[:3]:
+            assert stats[0][col_name].get("sum") == 0
+        # Sum for decimal column is a string
+        assert stats[0]["d"].get("sum") == "0"
+
+        assert stats[0]["g"].get("number_of_values") == 0
+        assert stats[0]["g"].get("has_null") is True
+        assert stats[0]["g"].get("true_count") == 0
+        assert stats[0]["g"].get("false_count") == 0
+
+        assert stats[0]["h"].get("number_of_values") == 0
+        assert stats[0]["h"].get("has_null") is True
+        assert stats[0]["h"].get("sum") == 0
+
+        assert stats[0]["i"].get("number_of_values") == 1
+        assert stats[0]["i"].get("has_null") is False
+        assert stats[0]["i"].get("minimum") == 1
+        assert stats[0]["i"].get("maximum") == 1
+        assert stats[0]["i"].get("sum") == 1