Storing null values in avro files

To be able to set Avro field to null you should allow this in Avro schema, by adding null as one of the possible types of the field. Take a look on example from Avro documentation:

{
  "type": "record",
  "name": "MyRecord",
  "fields" : [
    {"name": "userId", "type": "long"},              // mandatory field
    {"name": "userName", "type": ["null", "string"]} // optional field 
  ]
}

here userName is declared as composite type which could be either null or string. This kind of definition allows to set userName field to null. As contrast userId can only contain long values, hence attempt to set userId to null will result in NullPointerException.

I have this issue too and now resolved it.

I found @Nullable annotation in Apache Avro to declare the field is nullable.

So, in this example, we should

import org.apache.avro.reflect.Nullable;

public class MyAvroRecord {
    long id;
    String name;
    String type;
    Date timestamp;
    Date lastModifcationDate;
    String lastModifiedUsername;
    @Nullable
    Boolean lockedQuery;
}