DataWorks:Perform reverse modeling on physical tables

Limits

You can perform reverse modeling only on tables within a MaxCompute or E-MapReduce (EMR) Hive compute engine instance in the production environment.

Reverse modeling process

Procedure

1. Go to the Reverse Modeling page.

   1. Log on to the DataWorks console. In the left-side navigation pane, choose Data Modeling and Development > Data Modeling. On the page that appears, select the desired workspace from the drop-down list and click Go to Data Modeling.

   2. In the top navigation bar of the Data Modeling page, click Dimensional Modeling. In the left-side navigation pane, click Reverse Modeling to go to the Reverse Modeling page.

2. Start reverse modeling.

   • If this is the first time you use the reverse modeling feature, click Start Now on the Reverse Modeling page.

   • For subsequent use, click Create in the upper-right corner of the Modeling Tasks page.

3. Configure a reverse modeling policy.

   Note

   The reverse modeling operation is irreversible, and a reverse modeling policy cannot be modified after it is created and used. We recommend that you plan a reverse modeling policy in advance based on your business requirements.

   1. In the Create Reverse Policy step, configure the parameters.

      

      Parameter	Description
      Workspace	The DataWorks workspace to which the physical tables on which you want to perform reverse modeling belong. Note You can select only a workspace to which the current logon account is added as a member. For more information, see Manage permissions on workspace-level services.
      Compute Engine Type	The compute engine type of the compute engine instance within which the physical tables that will be used for reverse modeling exist. The compute engine instance is in the production environment.
      Compute Engine Instance	The name of the compute engine instance within which the physical tables that will be used for reserve modeling exist.
      Table Name Matching Rule	The rule based on which the system matches the names of physical tables in the selected compute engine instance. The system creates tables on the Dimensional Modeling page based on the matched physical tables. Valid values: Fuzzy Match: If you select this matching rule and enter a keyword in the field, the system matches all physical tables whose names contain the keyword. Exact Match: If you select this matching rule, you must enter the complete names of all physical tables on which you want to perform reverse modeling. Note If you select Exact Match for the Table Name Matching Rule parameter and you want to enter multiple table names, you must separate the table names with semicolons (;) that are not followed by spaces. If no physical tables are matched, reverse modeling fails, and no tables are created.
      Data Layer of Model After Reverse Modeling	Common Layer: If you want to create fact tables, dimension tables, or aggregate tables, set the parameter to this value. Application Layer: If you want to create application tables or dimension tables, set the parameter to this value.
      Table Naming Rule	The naming convention based on which the system parses the matched physical tables and standardizes the names of tables to be created during reverse modeling. The system stores the created tables at appropriate data layers based on the parsing results. Parsing rules The system parses the physical tables matched by using the method specified by the Table Name Matching Rule parameter, and the number of underscores (_) contained in each table name. A table name can contain a maximum of nine underscores (_) and can contain items such as the business process name, data domain name, and custom content between two underscores (_). If the system identifies that the name of a physical table contains the name of a data warehousing level, the system creates a table with the same name and stores the table at the data warehousing level. Note If the name of a physical table does not contain the name of a data warehousing level, such as the name of a data domain or business process, the data warehousing level of the physical table displayed in the Confirm Model Information step is empty. In this case, you can select a data warehousing level for the physical table in the Confirm Model Information step. Parsing methods Use a table name checker: You can select a created checker. This way, the system parses the names of physical tables based on the naming convention defined in the checker. For information about how to create and use a checker, see Configure and use a checker at a data layer. Configure a custom table naming convention: If you set the Table Naming Rule parameter to Custom Rule, you can combine options such as Business Process, Data Domain, Business Category, and Custom into a table naming convention based on your business requirements. Then, the system parses the names of physical tables based on the naming convention.
      Execution Method	The method used to create tables. Valid values: Full Update: If you set the parameter to this value, the system creates tables based on all matched physical tables on the Dimensional Modeling page. If you want the system to create tables based on all matched physical tables on the Dimensional Modeling page, select this method. Note If you select Full Update for the Execution Method parameter and a table that meets the matching rule already exists on the Dimensional Modeling page, the system deletes the existing table and re-creates a table. Incremental Update: If you set the parameter to this value, the system performs the following operations on the matched physical tables: Identifies and retains the existing tables that meet the matching rule on the Dimensional Modeling page. Creates only the tables that do not exist on the Dimensional Modeling page. If some tables have been created on the Dimensional Modeling page and the tables remain unchanged, you can select this method.

   2. Click Create Model. The system parses physical tables based on the reverse modeling policy.

4. Confirm information about the matched physical tables.

   1. Confirm information about the matched physical tables.

      The system creates tables based on the matched physical tables and the reverse modeling policy. You can modify information such as the table type, data layer, and data domain for the matched physical tables based on your business requirements. If you no longer need to perform reverse modeling on a physical table, you can remove the table from the Parsed Tables section in the Confirm Model Information step.

   2. Click Generate Model to finalize the tables.

5. View reverse modeling results.

   After reverse modeling is complete, you can view the numbers of different types of tables that are created and view the details of the tables that fail to be created in the Completed step. You can click Error Logs in the Actions column of a table that fails to be created to view error information and troubleshoot issues at the earliest opportunity.

   Note

   • The created tables are automatically materialized to the related compute engine instance. You do not need to manually publish the tables.

   • You can manage the created tables on the Dimensional Modeling page. For more information, see Publish and manage a table.

   

View reverse modeling tasks