Alter table

[Phani1]

Hi Team, Could you please suggest, Do we have an alternate approach to alter the table instead of creating a new table and copying the data as part of the deployment.

[Kaniz_Fatma]

Hi @Phani1, When deploying changes to a table in Azure Databricks, you can use an alternate approach to alter the table without creating a new one and copying data. Here are some options:

ALTER TABLE Statement:

• The ALTER TABLE statement allows you to modify the schema or properties of an existing table. You can use it to:
  • Rename the table within the same schema.
  • Add new columns to the table.
  • Alter properties or the location of existing columns.
  • Drop columns from the table.
  • Rename columns.
  • Add constraints (check, foreign key, or primary key).
  • And more!

Delta Lake Specific:

• If you’re using Delta Lake, consider using the REPLACE clause when creating a table. This preserves the table history and is recommended over dropping and re-creating tables.
• Delta Lake also supports type changes and renaming columns using the REWRITE feature.

Renaming Existing Tables:

• If you want to keep the existing data but rename the table, you can follow these steps:
  1. Create a new table (e.g., NewTable) with the desired schema.
  2. Copy the relevant data from the old table (e.g., OldTable) to the new table.
  3. Rename the old table (e.g., OldTable_History).
  4. Finally, rename the new table to the original table name (e.g., OldTable).

Adjust the table names and conditions according to your use case. Choose the approach that best fits your requirements and existing data. Happy deploying! 🚀🔍

For more detailed syntax and examples, refer to the official documentation.