Skip to main content

Schema Evolution

This page explains how InterSystems TotalView™ For Asset Management accommodates changes while also preserving your data, a process known as schema evolution.

How the System Manages Changes to Schemas

Schema evolution works as follows:

  1. When you import a schema and first edit it, the schema is a draft and cannot be used by recipes.

  2. When you publish a schema, it can then be used by recipes—specifically in a staging activity (which loads data into the system).

  3. When you define a recipe, each of its activities is initially a draft.

  4. When you publish a staging activity of a recipe, the system then generates the table that will store the data to be loaded.

  5. When you edit or reimport a schema, you are implicitly creating a draft that is not yet used by anything. The existing schema is unchanged; existing data is also unchanged.

    While a schema is in draft state, you have the option of deleting the draft (and reverting to the previous published version).

  6. When you republish a schema, if the change affects the structure needed to contain the data, the system automatically increments the version number of the schema and automatically generates a new draft of any staging activity that is affected by this change. The new staging activity draft is not automatically published, and the previous staging activity is unchanged.

  7. When you republish a staging activity, the system generates a new table as needed, considering the structural change that has occurred. This leaves the old table (and its data) unchanged.

Similarly, changes to earlier parts of a recipe can affect later activities in a recipe, requiring changes in those later activities. The system detects these changes, automatically generates draft activities where appropriate, and notifies you of the drafts.

See Also

FeedbackOpens in a new tab