Teams scaling ClickHouse commonly face a mix of architectural, performance, and operational challenges. As data volume and query concurrency grow, poorly designed schemas, unoptimized partitioning, and uneven sharding can lead to hotspots, long merges, and unpredictable latency. Managing background operations (merges, mutations, TTL, replication) becomes harder at scale and may compete with foreground queries for CPU, memory, and disk I/O. Ensuring consistent replication and fault tolerance across many nodes requires careful topology design, capacity planning, and automation. Visibility into cluster health, slow queries, and storage growth is essential but can be complex without robust monitoring and alerting. Additionally, cost optimization, multi-tenant isolation, and safe rollout of configuration or version changes become critical to avoid outages. Successful scaling demands continuous tuning, observability, and disciplined operational practices.