The original SQL processors implemented BigDecimal values as Strings for
Avro, as the version of Avro it used (1.7.6) did not support DECIMAL type.
As of Avro 1.7.7 (
AVRO-1402), this type is supported and so the SQL /HiveQL processors should be updated to handle BigDecimals correctly if possible.
UPDATED: This JIRA improved only ExecuteSQL and QueryDatabaseTable processors. SelectHiveQL is removed from target. Hive tables can be queried by ExecuteSQL/QueryDatabaseTable once
NIFI-3093 is resolved (and logical types will also be supported with those processors).