[PARQUET-1917] [parquet-proto] default values are stored in oneOf fields that aren't set

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.12.0
• Fix Version/s: 1.12.0
• Component/s: parquet-protobuf
• Assignee: Aaron Blake Niskode-Dossett
• Reporter: Aaron Blake Niskode-Dossett
• Created: 29/Sep/20 15:55
• Updated: 27/Jan/21 14:33
• Resolved: 22/Oct/20 14:55

Description

SCHEMA
--------

message Person {
  int32 foo = 1;
  oneof optional_bar {
    int32 bar_int = 200;
    int32 bar_int2 = 201;
    string bar_string = 300;
  }
}

 
CODE
--------
I set values for foo and bar_string
 

for (int i = 0; i < 3; i += 1) {
                com.etsy.grpcparquet.Person message = Person.newBuilder()
                        .setFoo(i)
                        .setBarString("hello world")
                        .build();
                message.writeDelimitedTo(out);
            }

And then I write the protobuf file out to parquet.
 
RESULT
-----------

$ parquet-tools show example.parquet                                                                                                                        
+-------+-----------+------------+--------------+
|   foo |   bar_int |   bar_int2 | bar_string   |
|-------+-----------+------------+--------------|
|     0 |         0 |          0 | hello world  |
|     1 |         0 |          0 | hello world  |
|     2 |         0 |          0 | hello world  |
+-------+-----------+------------+--------------+

 
bar_int and bar_int2 should be EMPTY for all three rows since only bar_string is set in the oneof.  0 is the default value for int, but it should not be stored.