Global Identifiers (GUIDs)

Introduction to GUIDs:

In Oracle Data Integrator (ODI) 12c, a significant change is the introduction of Globally Unique Identifiers (GUIDs) to ensure the uniqueness of objects across multiple work repositories. This new method of object identification is a step forward from previous versions of ODI, which used internal identifiers that were limited to a specific repository.

Key Concepts and Changes in ODI 12c:

1. What are GUIDs?
• A Global Unique Identifier (GUID) is a 128-bit value assigned to objects to guarantee their uniqueness across all work repositories, including multiple environments.
• GUIDs are generated using Java’s random UUID implementation. This ensures that each object within ODI (e.g., models, mappings, scenarios) has a unique identifier, irrespective of the repository or environment in which it resides.
2. Why are GUIDs Introduced in ODI 12c?
• In previous versions (such as ODI 11g), object identifiers were internal to a specific repository, meaning that objects with the same name could have different internal IDs when transferred between repositories or environments.
• In ODI 12c, GUIDs ensure that objects maintain consistent and unique identities across multiple repositories, improving object management, traceability, and migration between different instances of ODI.
3. Backward Compatibility:
• For users upgrading from ODI 11g to ODI 12c, backward compatibility is maintained through the use of Internal Identifiers.
• Internal Identifiers (also called internal IDs) are still available, but they are only relevant when using ODI in 11g compatibility mode.
• When operating in 11g compatibility mode, ODI continues to use the old method of referencing objects, with internal identifiers being managed in a way that works across repositories.
4. How GUIDs Are Assigned:
• Whenever a new ODI entity is created in ODI 12c, a GUID is automatically generated and assigned to the object.
• This GUID is a randomly generated identifier that is globally unique, ensuring that the object can be consistently identified across different work repositories and systems.
5. Handling GUIDs During Import/Export:
• Importing Export Files from Pre-12c Releases:
• When importing export files from earlier versions of ODI (before 12c), GUIDs cannot be directly generated as the object identifiers from previous releases may not match the new GUID format.
• To handle this scenario, a Global Upgrade Key is required during the repository upgrade process. This key ensures that GUIDs for objects imported from ODI 11g can be consistently recalculated and uniquely mapped after the upgrade.
• The Global Upgrade Key is a unique identifier used during the upgrade to ensure that the same GUID is generated for each object imported from the previous version of ODI. This key allows ODI to maintain compatibility and ensure that the objects' identities remain consistent during the transition from 11g to 12c.
• Import Upgrade Key:
• When importing an export file from a pre-12c ODI instance, the user must provide an Import Upgrade Key. This key helps ODI in the import process to calculate the GUIDs consistently.
• The Import Upgrade Key is typically the same as the Global Upgrade Key that was used during the upgrade process. However, it is not mandatory for the two keys to be identical, but using the same key simplifies the upgrade and ensures consistent object handling across repositories.
6. Advantages of GUIDs in ODI 12c:
• Unambiguous Object Identification: GUIDs guarantee that each object in ODI has a unique identifier, no matter where the object is located (different repositories or environments).
• Better Object Synchronization: This consistency in object identification makes it easier to migrate, export, and import objects between ODI repositories, especially when moving between different environments or versions of ODI.
• Simplified Data Management: GUIDs provide global uniqueness, making object management and traceability more reliable, especially in large-scale deployments or distributed ODI environments.
• Seamless Upgrades: When upgrading from ODI 11g to 12c, GUIDs ensure that existing objects are upgraded correctly without conflicts in identifiers, allowing smooth transitions without losing any metadata integrity.
7. GUID Format:
• A GUID is a 128-bit value and typically represented as a hexadecimal string (e.g., e0e9d6d2-d5d3-4bcb-9bfe-f55f736cbb33).
• This format is large enough to ensure global uniqueness and avoid any collisions between GUIDs generated in different systems, even across different ODI work repositories.

ODI Compatibility Modes and GUIDs:

1. 11g Compatibility Mode:
• In 11g compatibility mode, internal identifiers are maintained across repositories as they were in ODI 11g. However, for ODI 12c operations, GUIDs are still generated for new objects, but existing 11g objects will continue using their internal identifiers unless they are upgraded to use GUIDs.
• This compatibility mode allows for the smooth integration of legacy 11g content into an upgraded ODI 12c environment without breaking the repository structure.
2. Upgrading to ODI 12c:
• When upgrading from ODI 11g to 12c, GUIDs are introduced for new objects, but existing objects in the ODI 11g repository will still be identified using their internal identifiers.
• During the upgrade process, the Global Upgrade Key helps in consistently generating GUIDs for these objects.
• This upgrade key ensures that imported objects from ODI 11g are assigned the same GUIDs they would have had if they had been created in ODI 12c.
3. Repository Upgrade Process:
• The upgrade process requires careful handling of both internal identifiers (for backward compatibility) and GUIDs (for forward compatibility with ODI 12c and beyond).
• The Global Upgrade Key ensures that all ODI 11g objects are uniquely identified and compatible when migrated into the new 12c system.

Summary of GUIDs and Key Points:

• GUIDs are introduced in ODI 12c to ensure the global uniqueness of object identifiers across multiple work repositories.
• For backward compatibility, internal identifiers are still used when ODI is operating in 11g compatibility mode.
• GUIDs are automatically assigned to objects during creation, but special handling is required during the upgrade and import processes.
• The Global Upgrade Key is necessary to ensure consistent GUID generation during the upgrade process, particularly for imported objects from ODI 11g.
• The Import Upgrade Key is used during the import process to handle objects from older ODI versions and ensure GUID consistency.

By introducing GUIDs, ODI 12c improves object traceability and migration, enhancing the robustness of data integration workflows across different environments and repositories.