Behavior changes

This release of the Cloudera Data Warehouse (CDW) service on CDP 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 CDP web interface and navigate to the Data Warehouse service.
2. From the 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 CDW 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');