The following methods in AvroDeserializer keeps regenerating TypeInfo objects for every nullable field in a row.
This is happening in the following methods.
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.
Moreover the cache in SchemaToTypeInfo class does not help in nullable Avro records case as checking if an Avro record schema object already exists in the cache requires traversing 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 might be to make use of the column TypeInfo which is already passed in the worker method.