How it is serialized/deserialized is determined by specific serde. NULL is serialized as \N by SimpleLazySerDe (default serde for text). RCFile (ColumnarSerDe) uses the same default parameters as LazySimpleSerDe.
Unless I missed something, NULL serialization/deserialization is type independent (at least in LazySimpleSerDe). On Aug 9, 2010, at 9:42 AM, Pradeep Kamath wrote: Hi, What value does hive expect in the data for a column to be treated as null? I tried some permutations on a text data based table but couldn’t figure out what the correct representation was. I tried empty string, the string NULL and the string null for a string column and in all three cases the “is null” operator returned false. A couple of related questions: - Does the representation of null depend on the type of the column – is it different for string Vs non-string columns? - Is the representation of null different for different storage formats – text Vs RCFile Vs SequenceFile – I am particularly interested in text and RCFile. Thanks in advance, Pradeep
