ClickHouse architecture is a distributed, columnar, MPP (massively parallel processing) OLAP database built around the MergeTree family of table engines. It’s engineered to run analytical queries over billions of rows with sub-second latency by combining columnar storage, data skipping indexes, vectorised execution, and highly parallel query processing across shards and replicas.
Core elements of a production ClickHouse architecture:
- MergeTree table engines: The heart of ClickHouse — ReplicatedMergeTree, ReplacingMergeTree, AggregatingMergeTree, CollapsingMergeTree, and SummingMergeTree for different data-shape needs
- Sharding and replication: Distributed tables spread data across shards for throughput; ReplicatedMergeTree + Keeper (or ZooKeeper) provide HA and consistency per shard
- Storage layout: Columnar storage with part-based, sorted data files — optimised for range scans and aggregations
- Data skipping indexes: Min/max, bloom, and set indexes to skip irrelevant granules at query time
- Materialized views and projections: Pre-aggregated, continuously maintained views for sub-second dashboards
- Ingestion patterns: Kafka table engine for streaming ingest, S3 / HTTP for bulk, native protocol for low-latency writes
- Query engine: Vectorised, SIMD-aware execution with parallel query processing across threads, shards, and replicas
- Integration with streaming: ClickHouse sits naturally after Apache Flink and Apache Kafka — making it the serving layer of a modern streaming data platform
Operational concerns that make a ClickHouse architecture production-grade: capacity planning (RAM vs storage trade-offs), part-merge tuning, zero-downtime upgrades, backup and replication strategies, multi-tenant isolation via RBAC and resource quotas, and storage-tiering for cost control.
Acosom designs and operates ClickHouse architecture as the real-time analytics database inside streaming data platforms — on-prem, hybrid, or sovereign cloud — for regulated enterprises that need sub-second analytics over live event data.