From 005949b79aa7581557d0545fd9eed1b60616ea95 Mon Sep 17 00:00:00 2001
From: Dave Baranec <dbaranec@nvidia.com>
Date: Wed, 27 Apr 2022 16:02:13 -0500
Subject: [PATCH] Fix an issue with one_level_list schemas which were causing
 nesting information to propagate between columns, causing crashes.

---
 cpp/src/io/parquet/reader_impl.cu             |   4 +++
 .../data/parquet/one_level_list2.parquet      | Bin 0 -> 656 bytes
 python/cudf/cudf/tests/test_parquet.py        |  26 ++++++++++++++++++
 3 files changed, 30 insertions(+)
 create mode 100644 python/cudf/cudf/tests/data/parquet/one_level_list2.parquet

diff --git a/cpp/src/io/parquet/reader_impl.cu b/cpp/src/io/parquet/reader_impl.cu
index 46b3206f731..bbafcc40aa9 100644
--- a/cpp/src/io/parquet/reader_impl.cu
+++ b/cpp/src/io/parquet/reader_impl.cu
@@ -679,6 +679,10 @@ class aggregate_reader_metadata {
           }
 
           std::copy(nesting.cbegin(), nesting.cend(), std::back_inserter(input_col.nesting));
+
+          // pop off the extra nesting element.
+          if (schema_elem.is_one_level_list()) { nesting.pop_back(); }
+
           path_is_valid = true;  // If we're able to reach leaf then path is valid
         }
 
diff --git a/python/cudf/cudf/tests/data/parquet/one_level_list2.parquet b/python/cudf/cudf/tests/data/parquet/one_level_list2.parquet
new file mode 100644
index 0000000000000000000000000000000000000000..cd5acd045949218a7a419c66a11305eb7ddeb0d7
GIT binary patch
literal 656
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zrONEwN}89x_kG`c{mAt0F{FrgX}3oS94u<P9KV+($Egqu!DGUUF@_z|IzR!CE_G`Z
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z^MvC(D~||Etrm&O5F?K3Jo&auTh72jwgX%WStgnE?a76?e(plE6K-4K=4|fglcPB`
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z2<kq(B*p6{D{r0)?=36V%T?}$!6*p5Zn{}2;q{X=>5C*Ars=KdXCht5;W&zuER5r^
Uj7Cz#awr$_8WnI=rf?U(0hF3wRR910

literal 0
HcmV?d00001

diff --git a/python/cudf/cudf/tests/test_parquet.py b/python/cudf/cudf/tests/test_parquet.py
index 727200293f7..3a07ce6234c 100644
--- a/python/cudf/cudf/tests/test_parquet.py
+++ b/python/cudf/cudf/tests/test_parquet.py
@@ -2386,6 +2386,32 @@ def test_parquet_reader_one_level_list(datadir):
     assert_eq(expect, got)
 
 
+# testing a specific bug-fix/edge case.
+# specifically:  int a parquet file containing a particular way of representing
+#                a list column in a schema, the cudf reader was confusing
+#                nesting information between a list column and a subsequent
+#                string column, ultimately causing a crash.
+def test_parquet_reader_one_level_list2(datadir):
+    # we are reading in a file containing binary types, but cudf returns
+    # those as strings. so we have to massage the pandas data to get
+    # them to compare correctly.
+    def postprocess(val):
+        if isinstance(val, bytes):
+            return val.decode()
+        elif isinstance(val, np.ndarray):
+            return np.array([v.decode() for v in val])
+        else:
+            return val
+
+    fname = datadir / "one_level_list2.parquet"
+
+    expect = pd.read_parquet(fname)
+    expect = expect.applymap(postprocess)
+    got = cudf.read_parquet(fname)
+
+    assert_eq(expect, got, check_dtype=False)
+
+
 @pytest.mark.parametrize("size_bytes", [4_000_000, 1_000_000, 600_000])
 @pytest.mark.parametrize("size_rows", [1_000_000, 100_000, 10_000])
 def test_parquet_writer_row_group_size(