Schema Versioning for NoSQL Virtual Data Sources

Alation Cloud Service Applies to Alation Cloud Service instances of Alation

Customer Managed Applies to customer-managed instances of Alation

Available from release V R6 (5.10.x)

What is NoSQL Schema Versioning?

The metadata you load into a Generic NoSQL virtual data source (VDS) can be versioned to track changes to the data objects or data types.

We recommend that you enable schema versioning for a VDS that you know will have metadata in Avro format. Version history will reflect changes to data types in the uploaded Avro schemas.

Turn on schema versioning right after you create a NoSQL VDS but before you upload the metadata for the first time. This way, the first schema upload will become Version 1 of the metadata and all subsequent changes will be calculated off this first version.


Calculating changes for the schema version history make take time and slow down the NoSQL API when you use it to update your data source. Enable this feature only if version history is a must-have for your NoSQL VDS (when you are loading schemas in Avro format).

 Enabling Schema Versioning

Schema versioning can be enabled for each specific VDS of Generic NoSQL type that you create in Alation. By default, it is turned off.

To enable schema versioning,

  1. On the catalog page of the NoSQL VDS, on the upper right, click Settings to open the data source settings page:

  1. Click the General Settings tab and turn on the switch Enable Versioning for the Data Source. This enables schema versioning for this VDS. When it is enabled, you will see the Version History link for the uploaded schemas.


After being enabled, schema versioning cannot be disabled.


Viewing Change History for a Schema

To open the change history for a schema, click the Version History link on the catalog page of the schema:


Version History will show:

  • Schema versions

    • A version is an object that is created in the catalog after each API call that loads new and updates existing metadata to this data source. A version for a specific Avro schema is created only if this schema is affected by the API call.

  • Changes in the newer version as compared to one previous version

    • Type created

    • Type updated

    • Deleted


The Other Metadata field history is not captured. Version History only reflects changes to the data types and properties required by the API. See Supported Avro Data Types.


Filtering the List of Changes

You can filter the list of changes in the Version History using the quick filter on top of the table.

You can also sort the list of changes by Version.