This page provides an overview of heterogeneous database migration using the Database Migration Service conversion workspace or its legacy version. Conversion workspaces help you convert the schema and objects from your source database into a format that is compatible with your destination database. This conversion lets Database Migration Service migrate your data between the source and destination databases.
The conversion workspace includes a live conversion editor that lets you manipulate schema conversion in real time, as well as test and apply conversions to your destination database.
However, if you're using the Ora2Pg migration tool, then we recommend using the legacy conversion workspace. In such scenarios, the schema conversion process happens outside of Database Migration Service, and the workspace serves mainly as a connector between your source and destination databases.
The following table summarizes the differences between the workspace versions:
| New conversion workspace | Legacy conversion workspace |
|---|---|
| Schema and code object conversions happen in Database Migration Service. | You perform schema and code object conversions outside Database Migration Service by using the Ora2Pg migration tool. |
| You can apply converted sources to the destination database directly in Database Migration Service. | You are responsible for applying the converted schema to the destination database in your Cloud SQL for PostgreSQL destination instance. |
| You can test your draft schema and code directly in Database Migration Service to ensure they can be successfully applied to your destination instance. | You can't test your draft schema and code without affecting the destination instance. |
Automatically adds missing rowid columns for tables that
don't have primary keys. |
You must add missing primary keys to your source tables before converting schema. See Migrate tables without primary keys. |
Built-in conversion editor
The following sections provide an overview for editable code objects and conversion customizations that are available in the conversion workspace.
Editable Oracle objects
After you convert source database and code in the new conversion workspace, you can use the live editor to modify generated SQL for certain types of objects. The following Oracle objects are supported by the live editor:
- Table triggers (requires permission)
- Materialized views
- Packages
- Functions, stored procedures
- Synonyms
- Views
Additionally, some objects are converted but not available for editing directly inside Database Migration Service. To modify such objects, you need to perform the updates directly on the destination database after you apply the converted schema and code.
Objects that aren't supported for editing:
- Constraints
- Indexes
- User-defined object types
- Sequences
- Tables
Code and schema conversion support
The new conversion workspaces provide support for the following Oracle schema and code elements:
Supported Oracle schema elements
- Constraints
- Triggers (table level only)
- Indexes (only indexes which are created in the same schema as their table)
- Materialized Views
- Object Types (partial support)
- Packages
- Sequences
- Functions
- Stored Procedures
- Synonyms
- Tables
- Views
Supported Oracle PL/SQL code elements
- Triggers (table level only)
- Materialized Views
- Packages
- Functions
- Stored Procedures
- Views
Customizations support
Database Migration Service provides support for customizing your schema and code during conversion. The following customization features are available:
Rename entities
Available for supported schema and code elements and table columns. Supported rename directives:
Move entities
Moving entities can be achieved by using the
REPLACE_TABLES directive and specifying the full destination
table name (that is scheme.table).
Change data type
Available for table columns. Supported column type control directives: