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Dropping and recreating tables

You can drop and recreate tables in your data warehouse as required. If you change the model after the data warehouse tables have already been created and loaded with data, you should adjust the data warehouse to reflect the modified model (as described in Validating the data warehouse). Some changes however cannot be resolved by adjusting the data warehouse. In such cases, you can either revert the model to its pre-modified state or drop and (optionally) recreate the data warehouse tables.

Note that dropping and recreating tables will delete all of the data in the tables and should only be performed in lieu of a better option.

Information note

In some scenarios, you need to edit the CREATE table statements before they are run. This can be done using the Generate DDL scripts but do not run them in Project settings. For example, if your data warehouse tables contain partitions, you will need to edit the script to maintain the partitions.

To drop and recreate tables:

  1. In the Data Warehouse panel, select the Drop and Recreate Tables item from the menu in the top right corner. The Drop and Recreate Tables window opens.

  2. You can select to drop and/or recreate one or more of the following tables:

    • Data Warehouse & Data Marts - The data warehouse tables are derived from the model whereas the data mart tables are derived from the data warehouse tables.
    • Logging - These tables are generated when the task runs and contain logging information. By default, these tables are prefixed with the string "TLOG".

    • Intermediate - These tables are temporary tables that are created when the task runs. By default, these tables are prefixed with the string "TTMP".

      Information note

      Intermediate tables are created dynamically and therefore cannot be recreated.

    • Error Mart - These are the data mart exception tables. Data that is rejected by data quality rules will be copied to tables in the specified error mart schema. See also Error Mart.
    • Archive Tables - These are the tables that are created when the option to archive Change Tables after the changes have been applied (to the data warehouse tables) is selected. For more information, see Defining landing zones
  3. Click OK to perform the drop and/or recreate operation.

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