When Apache Iceberg creates tables, it stores the current NameNode address in the
metadata. If HDFS is running without High Availability (HA), Iceberg stores the
NameNode's hostname and port. If HDFS is configured with HA, it stores the nameservice
ID (example, nameservice1).
Consequently, modifying the HDFS configuration such as transitioning from a non-HA to an
HA setup or reverting from HA to non-HA, changes the NameNode address and invalidates
the stored address, rendering the existing data unreadable. In these scenarios, you must
export and re-import any existing Iceberg data after the HDFS changes are finalized to
maintain data accessibility.
For more information, see Create table feature using
Apache Iceberg.
