ClickHouse vs Streaming Databases: When to Use Which (2026)

ClickHouse is a columnar OLAP database optimized for fast analytical queries over large datasets. Streaming databases like RisingWave continuously process event streams and maintain incrementally updated views. Use ClickHouse for ad-hoc analytical queries over historical data. Use a streaming database for real-time materialized views with sub-second freshness. Many architectures use both.

Fundamental Difference

Aspect	ClickHouse (OLAP)	RisingWave (Streaming DB)
Processing model	Pull (query on read)	Push (update on write)
Data freshness	Seconds to minutes (after ingestion)	Sub-second (incremental)
Query pattern	Ad-hoc analytical queries	Pre-defined materialized views
Strengths	Complex queries over billions of rows	Known queries with strict freshness
Materialized views	Trigger-based (on INSERT only)	Continuous incremental (all changes)
State management	Local disk (MergeTree)	S3 (disaggregated)
SQL	ClickHouse SQL	PostgreSQL-compatible

ClickHouse Materialized Views vs Streaming Materialized Views

ClickHouse materialized views fire on INSERT — they process new rows as they're inserted. But they can't handle UPDATE or DELETE, and they don't support complex multi-table joins or windowed aggregations.

RisingWave materialized views are truly incremental — they handle INSERT, UPDATE, and DELETE, support complex joins across multiple streams, and update within milliseconds.

When to Use Both

Event Sources → RisingWave (real-time views, sub-second) → Applications
                    ↓
              Iceberg Sink
                    ↓
              ClickHouse (historical analytics, ad-hoc queries)

RisingWave handles real-time serving; ClickHouse handles historical analysis. Both read from the same data pipeline.

Frequently Asked Questions

Can ClickHouse replace a streaming database?

For simple append-only aggregations, ClickHouse materialized views may suffice. For CDC data (updates/deletes), complex joins, or sub-second consistency, a streaming database like RisingWave is necessary.

Is ClickHouse real-time?

ClickHouse ingests data quickly and queries are fast, but it's not a streaming system. Data must be inserted (batch or micro-batch) before it's queryable. A streaming database processes data continuously as it arrives.

Can I use RisingWave and ClickHouse together?

Yes. RisingWave processes streams and serves real-time views. RisingWave can sink data to ClickHouse (via Kafka or direct) for historical analytics. This is a common architecture pattern.