Prasanth Jayachandran created HIVE-10591:
--------------------------------------------
Summary: Support integer type promotion in ORC
Key: HIVE-10591
URL: https://issues.apache.org/jira/browse/HIVE-10591
Project: Hive
Issue Type: New Feature
Affects Versions: 1.3.0
Reporter: Prasanth Jayachandran
Assignee: Prasanth Jayachandran
ORC currently does not support schema-on-read. If we alter an ORC table with
'int' type to 'bigint' and if we query the altered table ClassCastException
will be thrown as the schema on read from table descriptor will expect
LongWritable whereas ORC will return IntWritable based on file schema stored
within ORC file. OrcSerde currently doesn't do any type conversions or type
promotions for performance reasons in inner loop. Since smallints, ints and
bigints are stored in the same way in ORC, it will be possible be allow such
type promotions without hurting performance. Following type promotions can be
supported without any casting
smallint -> int
smallint -> bigint
int -> bigint
Tinyint promotion is not possible without casting as tinyints are stored using
RLE byte writer whereas smallints, ints and bigints are stored using RLE
integer writer.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
