[jira] [Created] (HIVE-17394) AvroSerde is regenerating TypeInfo objects for each nullable Avro field in a row

["Ratandeep Ratti (JIRA)" <ji...@apache.org>]

Ratandeep Ratti created HIVE-17394:
--------------------------------------

             Summary: AvroSerde is regenerating TypeInfo objects for each nullable Avro field in a row
                 Key: HIVE-17394
                 URL: https://issues.apache.org/jira/browse/HIVE-17394
             Project: Hive
          Issue Type: Bug
    Affects Versions: 1.1.0
            Reporter: Ratandeep Ratti


The following methods in {{AvroDeserializer}} keep regenerating TypeInfo objects for every nullable  field in a row.

This is happening in the following methods.

{code}
private Object deserializeNullableUnion(Object datum, Schema fileSchema, Schema recordSchema) throws AvroSerdeException {
// elided
line 312:  return worker(datum, fileSchema, newRecordSchema,
            SchemaToTypeInfo.generateTypeInfo(newRecordSchema, null));
}
..
private Object deserializeSingleItemNullableUnion(Object datum, Schema Schema recordSchema)
// elided
line 357: return worker(datum, currentFileSchema, schema,
      SchemaToTypeInfo.generateTypeInfo(schema, null));
{code}

This is really bad in terms of performance. I'm not sure why didn't we use the TypeInfo we already have instead of generating again for each nullable field.  If you look at the {{worker}} method which calls the method {{deserializeNullableUnion}} the typeInfo corresponding to the nullable field column is already determined. Not sure why we have to determine that information again.

More the cache in SchmaToTypeInfo does not help in nullable Avro records case as checking if an Avro record schema object already exists in the cache requires traversing the all the fields in the record schema.

I've attached profiling snapshot which shows maximum time is being spent in the cache.

One way of fixing this IMO is to make use of the column TypeInfo which is already passed in the worker method.



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