From 58fa4bea1ff6ba57da217ae83c3f09f039cf180f Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Tue, 19 Apr 2022 08:59:15 -0700
Subject: [PATCH 1/3] Fix map nullable flag

---
 parquet/src/arrow/schema.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parquet/src/arrow/schema.rs b/parquet/src/arrow/schema.rs
index b0679e361819..55483876fce5 100644
--- a/parquet/src/arrow/schema.rs
+++ b/parquet/src/arrow/schema.rs
@@ -1018,7 +1018,7 @@ impl ParquetTypeConverter<'_> {
                         Box::new(Field::new(
                             key_item.name(),
                             DataType::Struct(vec![key, value]),
-                            false,
+                            self.schema.is_optional(),
                         )),
                         false, // There is no information to tell if keys are sorted
                     ))),

From aab053c68c8907c30fb02a8559f3bc47251b8977 Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Tue, 19 Apr 2022 17:22:08 -0700
Subject: [PATCH 2/3] Fix tests

---
 parquet/src/arrow/schema.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/parquet/src/arrow/schema.rs b/parquet/src/arrow/schema.rs
index 55483876fce5..b6424a50111e 100644
--- a/parquet/src/arrow/schema.rs
+++ b/parquet/src/arrow/schema.rs
@@ -1500,7 +1500,7 @@ mod tests {
                             Field::new("str", DataType::Utf8, false),
                             Field::new("num", DataType::Int32, false),
                         ]),
-                        false,
+                        true,
                     )),
                     false,
                 ),
@@ -1525,7 +1525,7 @@ mod tests {
                             Field::new("key", DataType::Utf8, false),
                             Field::new("value", DataType::Int32, true),
                         ]),
-                        false,
+                        true,
                     )),
                     false,
                 ),
@@ -2096,7 +2096,7 @@ mod tests {
                                     true,
                                 ),
                             ]),
-                            false,
+                            true,
                         )),
                         false, // fails to roundtrip keys_sorted
                     ),
@@ -2119,7 +2119,7 @@ mod tests {
                                     true,
                                 ),
                             ]),
-                            false,
+                            true,
                         )),
                         false, // fails to roundtrip keys_sorted
                     ),

From 380ba0a4b512f7990b0a29af0a4210768613b99f Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Tue, 19 Apr 2022 17:30:47 -0700
Subject: [PATCH 3/3] Add another map case

---
 parquet/src/arrow/schema.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/parquet/src/arrow/schema.rs b/parquet/src/arrow/schema.rs
index b6424a50111e..239311adec71 100644
--- a/parquet/src/arrow/schema.rs
+++ b/parquet/src/arrow/schema.rs
@@ -2125,6 +2125,29 @@ mod tests {
                     ),
                     true,
                 ),
+                Field::new(
+                    "c41",
+                    DataType::Map(
+                        Box::new(Field::new(
+                            "my_entries",
+                            DataType::Struct(vec![
+                                Field::new("my_key", DataType::Utf8, false),
+                                Field::new(
+                                    "my_value",
+                                    DataType::List(Box::new(Field::new(
+                                        "item",
+                                        DataType::Utf8,
+                                        true,
+                                    ))),
+                                    true,
+                                ),
+                            ]),
+                            false,
+                        )),
+                        false, // fails to roundtrip keys_sorted
+                    ),
+                    false,
+                ),
             ],
             metadata,
         );