Selective Overwrite to a Unity Catalog Table

[jp_allard]

I have been able to perform a selective overwrite using replace Where to a hive_metastore table, but when I use the same code for the same table in a unity catalog, no data is written.
Has anyone else had this issue or is there common mistakes that are made when preforming this?
Any help is much appreciated.

[Kaniz_Fatma]

Hi @jp_allard , 

• The Unity Catalog is a newer feature in Databricks, designed to replace the traditional Hive Metastore.
• When transitioning from Hive Metastore to Unity Catalog, there might be differences in behavior due to underlying architectural changes.
• If you’re upgrading your Hive Metastore schemas and external tables to Unity Catalog, consider using the SYNC command.
• The SYNC command allows seamless upgrades without data replication¹.
• For unsupported scenarios, you can use either CREATE TABLE AS SELECT (CTAS) or DEEP CLONE, but these...
• Ensure that the table names, paths, and other configuration settings are consistent between the Hive Metastore and Unity Catalog.
• Verify that the data you’re trying to overwrite exists in the Unity Catalog table.
• Check for any differences in partitioning, file formats, or other table properties.
• If your Databricks workspace was enabled for Unity Catalog after being in service with a Hive Metastore, you likely have data in the Hive Metastore that you want to continue using.
• Refer to the per-workspace Hive metastore documentation for guidance on using it alongside Unity Cat...³.
• Review the logs and error messages to identify any specific issues during the overwrite process.
• Inspect the query execution plan to see if there are any unexpected steps or missing data.