Effective in version 6.1, the performance and scalability of the legal hold functionality has been improved in the following ways:
You can resume a legal hold job from the point of failure.
Previously, when you resumed a legal hold job, the job restarted.
The query construction for legal hold is optimized. Child tables have a metadata column, either a tag or legal-hold column, that gets populated with the attribute applied to the parent. This allows the query to construct a join of just the child and immediate parent.
Previously, the query constructed a join that included the child, immediate parent, grandparent, and beyond. This strategy did not successfully scale to more than seven or eight levels.
Legal hold at the application level and unrelated-entity level does not depend on the relationship between tables. Because of this, any relation-based search or navigation on unrelated entities is not supported.