% python
>>> import pyarrow
>>> pyarrow.__version__
'24.0.0.dev298+g24f0f4c9a'
>>> from pyarrow import parquet as pq
>>> df = pq.read_table('src/parquet-testing/data/no_path_in_schema.zstd.parquet')
>>> df
pyarrow.Table
a: map<string, map<int32, bool ('value')> ('a')>
  child 0, a: struct<key: string not null, value: map<int32, bool ('value')>> not null
      child 0, key: string not null
      child 1, value: map<int32, bool ('value')>
          child 0, value: struct<key: int32 not null, value: bool not null> not null
              child 0, key: int32 not null
              child 1, value: bool not null
b: int32 not null
c: double not null
----
a: [[keys:["a"]values:[keys:[1,2]values:[true,false]],keys:["b"]values:[keys:[1]values:[true]],keys:["c"]values:[null],keys:["d"]values:[keys:[]values:[]],keys:["e"]values:[keys:[1]values:[true]],keys:["f"]values:[keys:[3,4,5]values:[true,false,true]]]]
b: [[1,1,1,1,1,1]]
c: [[1,1,1,1,1,1]]

% pqcli cat ~/src/parquet-testing/data/no_path_in_schema.zstd.parquet 
Argument error: Map key type must be binary (UTF8): required int32 key

% parquet-cli pages no_path_in_schema.parquet

Column: a.key_value.key
--------------------------------------------------------------------------------
  page   type  enc  count   avg size   size       rows     nulls   min / max
  0-D    dict  Z _  6       5.00 B     30 B      
  0-1    data  Z R  6       4.33 B     26 B                        


Column: a.key_value.value.key_value.key
--------------------------------------------------------------------------------
  page   type  enc  count   avg size   size       rows     nulls   min / max
  0-D    dict  Z _  5       4.00 B     20 B      
  0-1    data  Z R  9       3.78 B     34 B                        


Column: a.key_value.value.key_value.value
--------------------------------------------------------------------------------
  page   type  enc  count   avg size   size       rows     nulls   min / max
  0-0    data  Z _  9       3.33 B     30 B                        


Column: b
--------------------------------------------------------------------------------
  page   type  enc  count   avg size   size       rows     nulls   min / max
  0-D    dict  Z _  1       4.00 B     4 B       
  0-1    data  Z R  6       1.83 B     11 B                        


Column: c
--------------------------------------------------------------------------------
  page   type  enc  count   avg size   size       rows     nulls   min / max
  0-D    dict  Z _  1       8.00 B     8 B       
  0-1    data  Z R  6       1.83 B     11 B

% parquet-cli meta no_path_in_schema.zstd.parquet

File path:  no_path_in_schema.zstd.parquet
Created by: parquet-rs version 58.3.0
Properties:
                               ARROW:schema: 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
  org.apache.spark.sql.parquet.row.metadata: {"type":"struct","fields":[{"name":"a","type":{"type":"map","keyType":"string","valueType":{"type":"map","keyType":"integer","valueType":"boolean","valueContainsNull":false},"valueContainsNull":true},"nullable":true,"metadata":{}},{"name":"b","type":"integer","nullable":false,"metadata":{}},{"name":"c","type":"double","nullable":false,"metadata":{}}]}
Schema:
message arrow_schema {
  optional group a (MAP) {
    repeated group key_value {
      required binary key (STRING);
      optional group value (MAP) {
        repeated group key_value {
          required int32 key;
          required boolean value;
        }
      }
    }
  }
  required int32 b;
  required double c;
}


Row group 0:  count: 6  58.50 B records  start: 4  total(compressed): 351 B total(uncompressed):270 B 
--------------------------------------------------------------------------------
                                   type      encodings count     avg size   nulls   min / max
a.key_value.key                    BINARY    Z _ R     6         16.00 B            
a.key_value.value.key_value.key    INT32     Z _ R     9         10.44 B            
a.key_value.value.key_value.value  BOOLEAN   Z   _     9         5.22 B             
b                                  INT32     Z _ R     6         9.17 B             
c                                  DOUBLE    Z _ R     6         9.83 B