Scaling multi-tenant Go applications

Hierarchical partition keys in Azure Cosmos DB solve multi-tenant scaling challenges by enabling three-level partitioning (tenant, user, session) instead of single-level partitioning. This approach eliminates hot partitions, improves query efficiency, and provides better resource distribution for tenants of varying sizes. The Go SDK implementation demonstrates how to create containers with hierarchical partition keys and execute targeted queries that avoid expensive cross-partition operations, resulting in better performance and lower costs for SaaS applications.