Migration Best Practices

The following rules define best practices for migration.

If a piece of meta data must be propagated to a downstream environment, and Migration Wizard can migrate it, then Migration Wizard should migrate it.
Direct changes should not be made to migratable meta data in downstream environments.

These rules are especially important to Data Mart. This is because manual changes to downstream environments can set up situations in which components being migrated from a source environment may or may not already be present in the target, but a less than perfect match between source and target characteristics makes that matching ambiguous.

Migration Wizard contains logic for resolving cases where the best practices are not followed. This section discusses the logic used to resolve ambiguous meta data and how the system resolves them depending upon your configuration.

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Consistency of Model, Extension and Field IDs

For migration to succeed, the IDs of all models, extensions and fields must match between source and target environments.

These IDs originate in one of two ways. For the Fund Summary and detail-level models they are created by schema installation scripts. For all group-level models, model extensions, and Mart fields that you build, PACE initially assigns an ID using a "next instance" approach. Note that a model's ID is labeled "Name" in the Definition tab of the model user interface.

When a new model or field is migrated to a target environment, it takes the ID of the migrated component in the source environment and applies it to the target. So, if you strictly observe the best practices, you automatically have the required matching among source and target IDs.

But there is an important exception. You must still change the model IDs of the Fund Summary and detail-level models in all target environments to match the IDs of the corresponding models in the source environment. You do this by manually editing the Name field (which is the ID) of each model in the Definition tab of the model wizard. You can create model IDs that you find meaningful, like FUND_SUM or SEC_DETAIL, and use these in all models that you migrate. These IDs can contain up to 10 alphanumeric characters. They may duplicate across Mart instances, just not within Mart instances.

Migrate to Add New Content to Existing Models

Migration can handle both new and existing models in downstream environments. When you migrate Data Mart models, Migration Wizard gives you its standard options to Overwrite or Use Existing. If you use best practices, the choice does not matter because all target meta data matches its corresponding meta data in the source.

However, Migration Wizard does permit you to maintain some differences between models in source and target environments. Migration Wizard never deletes a field from a downstream environment in the course of migrating, whether you choose Overwrite or Use Existing. For more information, see Migration Conflicts.