Usage limits
While ClickHouse is known for its speed and reliability, optimal performance is achieved within certain operating parameters. For example, having too many tables, databases, or parts can negatively impact performance. To prevent this, ClickHouse Cloud enforces limits across several operational dimensions. The details of these guardrails are listed below.
If you've run up against one of these guardrails, it's possible that you are implementing your use case in an unoptimized way. Contact our support team and we will gladly help you refine your use case to avoid exceeding the guardrails or look together at how we can increase them in a controlled manner.
| Dimension | Limit |
|---|---|
| Databases | 1000 |
| Tables | 5000 |
| Columns | ∼1000 (wide format is preferred to compact) |
| Partitions | 50k |
| Parts | 100k across the entire instance |
| Part size | 150gb |
| Services per organization | 20 (soft) |
| Services per warehouse | 5 (soft) |
| Low cardinality | 10k or less |
| Primary keys in a table | 4-5 that sufficiently filter down the data |
| Query concurrency | 1000 (per replica) |
| Batch ingest | anything > 1M will be split by the system in 1M row blocks |
For Single Replica Services, the maximum number of databases is restricted to 100, and the maximum number of tables is restricted to 500. In addition, storage for Basic Tier Services is limited to 1 TB.
