Building a pain-free metadata store involves a series of best practices, beginning with understanding the nature of metadata, which can be broadly categorized into forensic and control data, with a focus on the latter due to its mission-critical nature and relational complexity. The process starts with selecting the right database tailored to specific needs rather than convenience, as illustrated by Rubrik's experience transitioning from Cassandra to CockroachDB for better consistency and performance. Thoughtful database schema design is crucial, requiring careful planning to avoid major adjustments post-deployment, and incorporating a "human schema" is essential to ensure that all team members, regardless of technical expertise, can access and understand the data through resources like a data dictionary. Schema changes should be additive to facilitate integration with existing application services and avoid disruptions, necessitating strategies for backfilling data when new columns are added. Finally, while migrations might eventually become necessary due to the evolving needs of an application, thorough upfront planning and adherence to these best practices can delay and mitigate the challenges associated with such transitions.