Usage limits

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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.

Tip

If you've run up against one of these guardrails, it's possible that you're
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.

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Dimension Limit|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Databases** 1000|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Tables** 5000|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Columns** ∼1000 (wide format is preferred to compact)|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Partitions** 50k|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Parts** 10k (see [`max_parts_in_total`](/docs/whats-new/cloud-compatibility#max_parts_in_total-10000) setting)| **Part size** 150gb|  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Services per organization** 20 (soft)|  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Services per warehouse** 5 (soft)|  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | **Replicas per service** 20 (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 | | | | | | | | | | | | | | | | | | | | | | | | | | | |

Note

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.

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