chDB
activeby ClickHouse, Inc. · since 2023
Embedded, in-process OLAP engine powered by ClickHouse, used mainly from Python.
Overview
chDB packages the ClickHouse engine as an in-process library, so a Python (or Go, Rust, Node, C) program can run ClickHouse SQL over Parquet, CSV, Arrow, pandas DataFrames, S3 or remote databases without a server. Sessions can persist tables to a local directory, and newer releases add a pandas-compatible DataStore API. It joined ClickHouse, Inc. in 2024. chDB gives you ClickHouse's function library and formats in a DuckDB-like footprint; it is single-process, the wheel is large, and its non-Python bindings are less mature.
Strengths & trade-offs
Strengths
- +Full ClickHouse SQL and function library inside a Python process
- +Reads 70+ formats including Parquet, Arrow and pandas DataFrames zero-copy
- +Queries S3, MySQL, Postgres and ClickHouse servers via table functions
- +Backed by ClickHouse, Inc. and tracks upstream releases
Trade-offs
- −Large binary/wheel size
- −Single-process, no concurrent multi-user access
- −Bindings outside Python are less mature
- −Smaller community than DuckDB
Great for
- +Notebook analytics with ClickHouse SQL
- +Local ETL on Parquet and CSV
- +Testing ClickHouse queries without a server
- +Embedding analytics in Python services
Think twice for
- −Multi-user server workloads
- −Windows-first environments
- −OLTP
Capabilities
Native or official first-party support · 7 of 25 tracked
Scale & consistency
- Comfortable data size
- Medium · ≤ 10 TB
- Horizontal scaling
- None
- Multi-region
- No
- Transactions
- None
- Consistency
- Strong
- Schema
- Strict
- Architecture
- Embedded, In memory, Single node
- Query languages
- SQL (ClickHouse dialect), Python DataFrame API
Single process using all local cores; bound by one machine.
Deployment
Ecosystem
Alternatives to chDB
In-process columnar SQL database: the SQLite of analytics, running inside your app or notebook.
chdb vs duckdb →Open-source columnar OLAP database known for very fast aggregations over billions of rows.
chdb vs clickhouse →Extensible Rust query engine library on Apache Arrow for building databases and data systems.
chdb vs apache-datafusion →Pure-JavaScript in-memory SQL engine for browsers and Node.js that queries arrays, JSON, CSV and Excel files.
chdb vs alasql →Serverless cloud data warehouse built on DuckDB, with hybrid local-plus-cloud execution.
chdb vs motherduck →Spark's SQL and DataFrame engine for large-scale batch, streaming and lakehouse processing.
chdb vs apache-spark-sql →chDB FAQ
What is chDB?
chDB is a columnar / OLAP database by ClickHouse, Inc., first released in 2023. chDB packages the ClickHouse engine as an in-process library, so a Python (or Go, Rust, Node, C) program can run ClickHouse SQL over Parquet, CSV, Arrow, pandas DataFrames, S3 or remote databases without a server. Sessions can persist tables to a local directory, and newer releases add a pandas-compatible DataStore API. It joined ClickHouse, Inc. in 2024. chDB gives you ClickHouse's function library and formats in a DuckDB-like footprint; it is single-process, the wheel is large, and its non-Python bindings are less mature.
Is chDB open source?
Yes. chDB is open source. License: Apache License 2.0.
Does chDB support ACID transactions?
No. chDB does not provide ACID transactions; its consistency model is strong.
Does chDB scale horizontally?
chDB does not scale horizontally; it runs on a single node, so you scale it up rather than out. It is comfortable at medium scale (≤ 10 TB).
How can I run chDB?
You can self-host it and embed it in your application.
What is chDB best for?
chDB is a strong fit for notebook analytics with ClickHouse SQL; local ETL on Parquet and CSV; and testing ClickHouse queries without a server. Think twice for multi-user server workloads.
What are the best alternatives to chDB?
Common alternatives to chDB include DuckDB, ClickHouse, Apache DataFusion, AlaSQL and MotherDuck. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
How popular is chDB?
chDB ranks #143 of 844 databases on the WhichDB Score (21.1/100), and #14 among columnar / OLAP databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.