12. How do I handle the exception displayed with a Tez Query while querying a JDBC table?

You would see the the following exception message when you are querying a JDBC table using Tez.

java.io.IOException: InputFormatWrapper can not support RecordReaders that don't return same key & value objects.

You get the exception as the JDBC Storage handler does not work when Input Splits Grouping is enabled in Hive-on-Tez. HiveInputFormat is enabled by default in Tez to support Splits Grouping.

You can avoid the issue by setting the input format as CombineHiveInputFormat using this command that disables the Splits Grouping.

set hive.tez.input.format=org.apache.hadoop.hive.ql.io.CombineHiveInputFormat;