Behavior changes

This release of the Cloudera Data Warehouse service on Cloudera Public Cloud has the following behavior changes:

Summary:

Change in value for the write.delete.mode property

Before this release:

The value for the write.delete.mode property was set to 'merge-on-read'.

After this release:

The default value for the write.delete.mode property is changed to 'copy-on-write'.

This change might result in issues while deleting Iceberg table records.

If you want to continue to use the 'merge-on-read' mode for new Iceberg tables, perform the following steps:

1. Log in to the Cloudera web interface and navigate to the Cloudera Data Warehouse service.
2. From the Cloudera Data Warehouse service, click Database Catalogs, locate your Database Catalog and then click > Edit.
3. In the Database Catalogs detail page, click Configurations > Metastore and select the hive-site configuration file.
4. Click and add the following configuration key and key value:

   write.delete.mode=merge-on-read

5. Click Apply Changes.
6. Click Virtual Warehouses, locate your virtual warehouse and then click > Edit.
7. In the Virtual Warehouse Details page, click Configurations > Hiveserver2 and select the hive-site configuration file.
8. Click and add the following configuration key and key value:

   write.delete.mode=merge-on-read

9. Click Apply Changes.

If you want to set 'merge-on-read' for older Iceberg tables that were created before upgrading to this Cloudera Data Warehouse version, perform the following steps:

1. Run the following queries to modify the table properties of the old Iceberg tables:

   ALTER TABLE [***OLD TABLE NAME***] SET TBLPROPERTIES('write.on.delete'='dummy');
   ALTER TABLE [***OLD TABLE NAME***] SET TBLPROPERTIES('write.on.delete'='merge-on-read');