clickhouse-rate-limits

# ClickHouse Rate Limits & Concurrency ## Overview ClickHouse does not have REST API rate limits like a SaaS product. Instead, it has server-side concurrency limits, memory quotas, and per-user settings that control resource usage. This skill covers how to configure and work within those limits. ## Prerequisites - ClickHouse admin access (or Cloud console) - Understanding of your concurrency requirements ## Instructions ### Step 1: Understand Server-Side Limits | Setting | Default | Description | |---------|---------|-------------| | `max_concurrent_queries` | 100 | Max queries running simultaneously | | `max_connections` | 4096 | Max TCP/HTTP connections | | `max_memory_usage` | ~10GB | Per-query memory limit | | `max_execution_time` | 0 (unlimited) | Per-query timeout in seconds | | `max_threads` | CPU cores | Threads per query | **ClickHouse Cloud API limit:** The Cloud management API (not the query interface) is limited to 10 requests per 10 seconds. ### Step 2: Configure Per-User Quotas ```sql -- Create a quota that limits query resources per user CREATE QUOTA IF NOT EXISTS app_quota FOR INTERVAL 1 HOUR MAX queries = 10000, result_rows = 100000000, read_rows = 1000000000, execution_time = 3600 TO app_user; -- Create a profile with resource limits CREATE SETTINGS PROFILE IF NOT EXISTS app_profile SETTINGS max_memory_usage = 5000000000, -- 5GB per query max_execution_time = 30, -- 30s t...