replication-guide

What problem does it solve?

This Skill eliminates operational friction for self-hosted ClickHouse operators managing ReplicatedMergeTree clusters, addressing common pain points like replication lag, stuck readonly replicas, split brain scenarios, and Keeper connectivity failures that disrupt data availability and cluster consistency.

Core Features & Use Cases

• Replication Health Monitoring: Quickly diagnose cluster health using system tables to check replication delay, queue size, and replica status.
• Failover & Recovery Workflows: Follow safe, step-by-step procedures to restore readonly replicas, remove corrupted replicas, and sync diverged data without accidental data loss.
• Quorum & Keeper Configuration: Configure quorum writes to protect critical data from node failures, and manage ClickHouse Keeper (the modern ZooKeeper replacement) for reliable metadata storage.
• Use Case: If a ClickHouse replica becomes readonly after a temporary network outage, use this Skill to verify Keeper connectivity, restore write access, and confirm all replicas are fully caught up.

Quick Start

Use the replication-guide skill to diagnose why your ClickHouse ReplicatedMergeTree replica is stuck in readonly mode and restore normal write access.