clickhouse-rate-limits

name	clickhouse-rate-limits
description	Configure ClickHouse query concurrency, memory quotas, and connection limits. Use when hitting "too many simultaneous queries", managing concurrent users, or tuning server-side resource limits. Trigger: "clickhouse rate limit", "clickhouse concurrency", "clickhouse quota", "too many simultaneous queries", "clickhouse connection limit".
allowed-tools	Read, Write, Edit
version	1.0.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","database","analytics","clickhouse","olap"]
compatible-with	claude-code

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

-- 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  ,      
        max_execution_time  ,             
        max_threads  ,                     
        max_concurrent_queries_for_user   
     app_user;