Java Clients Overview
ClickHouse Client
Java client is a library implementing an API that abstracts details of network communications with ClickHouse server. Currently only HTTP interface is well supported. The library provides all need to send requests and parse responses.
First Java client was developed far back in 2015. We have refactored it in 2024 and have introduced a new component - client-v2. New implementation has
new improved API, new underlying implementation and many other improvements.
Supported Data Types
| Data Type | Client V2 Support | Client V1 Support |
|---|---|---|
| Int8 | ✔ | ✔ |
| Int16 | ✔ | ✔ |
| Int32 | ✔ | ✔ |
| Int64 | ✔ | ✔ |
| Int128 | ✔ | ✔ |
| Int256 | ✔ | ✔ |
| UInt8 | ✔ | ✔ |
| UInt16 | ✔ | ✔ |
| UInt32 | ✔ | ✔ |
| UInt64 | ✔ | ✔ |
| UInt128 | ✔ | ✔ |
| UInt256 | ✔ | ✔ |
| Float32 | ✔ | ✔ |
| Float64 | ✔ | ✔ |
| Decimal | ✔ | ✔ |
| Decimal32 | ✔ | ✔ |
| Decimal64 | ✔ | ✔ |
| Decimal128 | ✔ | ✔ |
| Decimal256 | ✔ | ✔ |
| Bool | ✔ | ✔ |
| String | ✔ | ✔ |
| FixedString | ✔ | ✔ |
| Nullable | ✔ | ✔ |
| Date | ✔ | ✔ |
| Date32 | ✔ | ✔ |
| DateTime | ✔ | ✔ |
| DateTime32 | ✔ | ✔ |
| DateTime64 | ✔ | ✔ |
| Interval | ✗ | ✗ |
| Enum | ✔ | ✔ |
| Enum8 | ✔ | ✔ |
| Enum16 | ✔ | ✔ |
| Array | ✔ | ✔ |
| Map | ✔ | ✔ |
| Nested | ✔ | ✔ |
| Tuple | ✔ | ✔ |
| UUID | ✔ | ✔ |
| IPv4 | ✔ | ✔ |
| IPv6 | ✔ | ✔ |
| Object | ✗ | ✔ |
| Point | ✔ | ✔ |
| JSON | ✔ | ✔ |
| Nothing | ✔ | ✔ |
| MultiPolygon | ✔ | ✔ |
| Ring | ✔ | ✔ |
| Polygon | ✔ | ✔ |
| SimpleAggregateFunction | ✔ | ✔ |
| AggregateFunction | ✗ | ✔ |
Note
- AggregatedFunction - ⚠️ does not support
SELECT * FROM table ... - Decimal -
SET output_format_decimal_trailing_zeros=1in 21.9+ for consistency - Enum - can be treated as both string and integer
- UInt64 - mapped to
longin client-v1
Features
Table of features of the clients:
| Name | Client V2 | Client V1 | Comments |
|---|---|---|---|
| Http Connection | ✔ | ✔ | |
| Http Compression (LZ4) | ✔ | ✗ | |
| Server Response Compression - LZ4 | ✔ | ✔ | |
| Client Request Compression - LZ4 | ✔ | ✔ | |
| HTTPs | ✔ | ✔ | |
| Client SSL Cert (mTLS) | ✔ | ✔ | |
| Http Proxy | ✔ | ✔ | |
| POJO SerDe | ✔ | ✗ | |
| Connection Pool | ✔ | ✔ | When Apache HTTP Client used |
JDBC Drive inherits same features as underlying client implementation. Other JDBC features are listed on its page.
Compatibility
- All projects in this repo are tested with all active LTS versions of ClickHouse.
- Support policy
- We recommend to upgrade client continuously to not miss security fixes and new improvements
- If you have an issue with migration - create and issue and we will respond!