[HIVE-10687] AvroDeserializer fails to deserialize evolved union fields

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: File Formats, Serializers/Deserializers
• Target Version/s: 1.3.0
• Assignee: Swarnim Kulkarni
• Reporter: Swarnim Kulkarni
• Created: 12/May/15 16:47
• Updated: 16/Feb/16 23:52
• Resolved: 27/Jun/15 23:34

Description

Consider the union field:

union {int, string}

and now this field evolves to

union {null, int, string}.

Running it through the avro schema compatibility check[1], they are actually compatible which means that the latter could be used to deserialize the data written with former. However the avro deserializer fails to do that. Mainly because of the way it reads the tags from the reader schema and then reds the corresponding data from the writer schema. [2]

[1] http://pastebin.cerner.corp/31078
[2] https://github.com/cloudera/hive/blob/cdh5.4.0-release/serde/src/java/org/apache/hadoop/hive/serde2/avro/AvroDeserializer.java#L354