Feature set spec with reserved spec should not be allowed to be registered #818

Expected Behavior

If a feature spec contains reserved column name such as created_timestamp, Feast should not allow the feature set to be registered at all.

Current Behavior

The feature set get registered, and job update fails due to duplicated column in bigquery schema.

Steps to reproduce

Create a feature spec that contains reserved column name.

Possible Solution

Feast client should perform verification on feature set spec prior to registering the feature set to Feast core.