Your team hash-sharded a single vector index across twe...

The core issue is treating compliance as a trade-off against technical performance or cost. Because data residency requirements are non-negotiable, the current sharding strategy is fundamentally flawed regardless of the performance gains achieved by hash-sharding.

To resolve this, you must first decouple the compliance requirements from the storage architecture. Once the illegal mixing is addressed, you should analyze the system to determine how much of the original capacity can be preserved by moving to a federated index model, rather than attempting to force a single, non-compliant index.