Official pure Rust typed client for ClickHouse DB.

• Uses serde for encoding/decoding rows.
• Supports serde attributes: skip_serializing, skip_deserializing, rename.
• Uses RowBinaryWithNamesAndTypes or RowBinary formats over HTTP transport.
  • By default, RowBinaryWithNamesAndTypes with database schema validation is used.
  • It is possible to switch to RowBinary, which can potentially lead to increased performance (see below).
  • There are plans to implement Native format over TCP.
• Supports TLS (see native-tls and rustls-tls features below).
• Supports compression and decompression (LZ4 and LZ4HC).
• Provides API for selecting.
• Provides API for inserting.
• Provides API for infinite transactional (see below) inserting.
• Provides mocks for unit testing.

Note: ch2rs is useful to generate a row type from ClickHouse.

Starting from 0.14.0, the crate uses RowBinaryWithNamesAndTypes format by default, which allows row types validation against the ClickHouse schema. This enables clearer error messages in case of schema mismatch at the cost of performance. Additionally, with enabled validation, the crate supports structs with correct field names and matching types, but incorrect order of the fields, with an additional slight (5-10%) performance penalty.

If you are looking to maximize performance, you could disable validation using Client::with_validation(false). When validation is disabled, the client switches to RowBinary format usage instead.

The downside with plain RowBinary is that instead of clearer error messages, a mismatch between Row and database schema will result in a NotEnoughData error without specific details.

However, depending on the dataset, there might be x1.1 to x3 performance improvement, but that highly depends on the shape and volume of the dataset.

It is always recommended to measure the performance impact of validation in your specific use case. Additionally, writing smoke tests to ensure that the row types match the ClickHouse schema is highly recommended, if you plan to disable validation in your application.

To use the crate, add this to your Cargo.toml:

[dependencies]
clickhouse = "0.13.3"

[dev-dependencies]
clickhouse = { version = "0.13.3", features = ["test-util"] }

use clickhouse::Client;

let client = Client::default()
    .with_url("http://localhost:8123")
    .with_user("name")
    .with_password("123")
    .with_database("test");

use serde::Deserialize;
use clickhouse::Row;

#[derive(Row, Deserialize)]
struct MyRow<'a> {
    no: u32,
    name: &'a str,
}

let mut cursor = client
    .query("SELECT ?fields FROM some WHERE no BETWEEN ? AND ?")
    .bind(500)
    .bind(504)
    .fetch::<MyRow<'_>>()?;

while let Some(row) = cursor.next().await? { .. }

use serde::Serialize;
use clickhouse::Row;

#[derive(Row, Serialize)]
struct MyRow {
    no: u32,
    name: String,
}

let mut insert = client.insert("some")?;
insert.write(&MyRow { no: 0, name: "foo".into() }).await?;
insert.write(&MyRow { no: 1, name: "bar".into() }).await?;
insert.end().await?;

let mut inserter = client.inserter("some")?
    .with_timeouts(Some(Duration::from_secs(5)), Some(Duration::from_secs(20)))
    .with_max_bytes(50_000_000)
    .with_max_rows(750_000)
    .with_period(Some(Duration::from_secs(15)));

inserter.write(&MyRow { no: 0, name: "foo".into() })?;
inserter.write(&MyRow { no: 1, name: "bar".into() })?;
let stats = inserter.commit().await?;
if stats.rows > 0 {
    println!(
        "{} bytes, {} rows, {} transactions have been inserted",
        stats.bytes, stats.rows, stats.transactions,
    );
}

inserter.end().await?;

client.query("DROP TABLE IF EXISTS some").execute().await?;

• lz4 (enabled by default) — enables Compression::Lz4. If enabled, Compression::Lz4 is used by default for all queries.
• inserter — enables client.inserter().
• test-util — adds mocks. See the example. Use it only in dev-dependencies.
• uuid — adds serde::uuid to work with uuid crate.
• time — adds serde::time to work with time crate.
• chrono — adds serde::chrono to work with chrono crate.

By default, TLS is disabled and one or more following features must be enabled to use HTTPS urls:

• native-tls — uses native-tls, utilizing dynamic linking (e.g. against OpenSSL).
• rustls-tls — enables rustls-tls-aws-lc and rustls-tls-webpki-roots features.
• rustls-tls-aws-lc — uses rustls with the aws-lc cryptography implementation.
• rustls-tls-ring — uses rustls with the ring cryptography implementation.
• rustls-tls-webpki-roots — uses rustls with certificates provided by the webpki-roots crate.
• rustls-tls-native-roots — uses rustls with certificates provided by the rustls-native-certs crate.

If multiple features are enabled, the following priority is applied:

• native-tls > rustls-tls-aws-lc > rustls-tls-ring
• rustls-tls-native-roots > rustls-tls-webpki-roots

How to choose between all these features? Here are some considerations:

• A good starting point is rustls-tls, e.g. if you use ClickHouse Cloud.
• To be more environment-agnostic, prefer rustls-tls over native-tls.
• Enable rustls-tls-native-roots or native-tls if you want to use self-signed certificates.

• (U)Int(8|16|32|64|128) maps to/from corresponding (u|i)(8|16|32|64|128) types or newtypes around them.

• (U)Int256 aren't supported directly, but there is a workaround for it.

• Float(32|64) maps to/from corresponding f(32|64) or newtypes around them.

• Decimal(32|64|128) maps to/from corresponding i(32|64|128) or newtypes around them. It's more convenient to use fixnum or another implementation of signed fixed-point numbers.

• Boolean maps to/from bool or newtypes around it.

• String maps to/from any string or bytes types, e.g. &str, &[u8], String, Vec<u8> or SmartString. Newtypes are also supported. To store bytes, consider using serde_bytes, because it's more efficient.

  Example

  #[derive(Row, Debug, Serialize, Deserialize)]
  struct MyRow<'a> {
      str: &'a str,
      string: String,
      #[serde(with = "serde_bytes")]
      bytes: Vec<u8>,
      #[serde(with = "serde_bytes")]
      byte_slice: &'a [u8],
  }

• FixedString(N) is supported as an array of bytes, e.g. [u8; N].

  Example

  #[derive(Row, Debug, Serialize, Deserialize)]
  struct MyRow {
      fixed_str: [u8; 16], // FixedString(16)
  }

• Enum(8|16) are supported using serde_repr. You could use #[repr(i8)] for Enum8 and #[repr(i16)] for Enum16.

  Example

  use serde_repr::{Deserialize_repr, Serialize_repr};
  
  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      level: Level,
  }
  
  #[derive(Debug, Serialize_repr, Deserialize_repr)]
  #[repr(i8)]
  enum Level {
      Debug = 1,
      Info = 2,
      Warn = 3,
      Error = 4,
  }

• UUID maps to/from uuid::Uuid by using serde::uuid. Requires the uuid feature.

  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      #[serde(with = "clickhouse::serde::uuid")]
      uuid: uuid::Uuid,
  }

• IPv6 maps to/from std::net::Ipv6Addr.

• IPv4 maps to/from std::net::Ipv4Addr by using serde::ipv4.

  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      #[serde(with = "clickhouse::serde::ipv4")]
      ipv4: std::net::Ipv4Addr,
  }

• Date maps to/from u16 or a newtype around it and represents a number of days elapsed since 1970-01-01. The following external types are supported:

  • time::Date is supported by using serde::time::date, requiring the time feature.
  • chrono::NaiveDate is supported by using serde::chrono::date, requiring the chrono feature.
  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      days: u16,
      #[serde(with = "clickhouse::serde::time::date")]
      date: Date,
      // if you prefer using chrono:
      #[serde(with = "clickhouse::serde::chrono::date")]
      date_chrono: NaiveDate,
  }

• Date32 maps to/from i32 or a newtype around it and represents a number of days elapsed since 1970-01-01. The following external types are supported:

  • time::Date is supported by using serde::time::date32, requiring the time feature.
  • chrono::NaiveDate is supported by using serde::chrono::date32, requiring the chrono feature.
  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      days: i32,
      #[serde(with = "clickhouse::serde::time::date32")]
      date: Date,
      // if you prefer using chrono:
      #[serde(with = "clickhouse::serde::chrono::date32")]
      date_chrono: NaiveDate,
  
  }

• DateTime maps to/from u32 or a newtype around it and represents a number of seconds elapsed since UNIX epoch. The following external types are supported:

  • time::OffsetDateTime is supported by using serde::time::datetime, requiring the time feature.
  • chrono::DateTime<Utc> is supported by using serde::chrono::datetime, requiring the chrono feature.
  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      ts: u32,
      #[serde(with = "clickhouse::serde::time::datetime")]
      dt: OffsetDateTime,
      // if you prefer using chrono:
      #[serde(with = "clickhouse::serde::chrono::datetime")]
      dt_chrono: DateTime<Utc>,        
  }

• DateTime64(_) maps to/from i64 or a newtype around it and represents a time elapsed since UNIX epoch. The following external types are supported:

  • time::OffsetDateTime is supported by using serde::time::datetime64::*, requiring the time feature.
  • chrono::DateTime<Utc> is supported by using serde::chrono::datetime64::*, requiring the chrono feature.
  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      ts: i64, // elapsed s/us/ms/ns depending on `DateTime64(X)`
      #[serde(with = "clickhouse::serde::time::datetime64::secs")]
      dt64s: OffsetDateTime,  // `DateTime64(0)`
      #[serde(with = "clickhouse::serde::time::datetime64::millis")]
      dt64ms: OffsetDateTime, // `DateTime64(3)`
      #[serde(with = "clickhouse::serde::time::datetime64::micros")]
      dt64us: OffsetDateTime, // `DateTime64(6)`
      #[serde(with = "clickhouse::serde::time::datetime64::nanos")]
      dt64ns: OffsetDateTime, // `DateTime64(9)`
      // if you prefer using chrono:
      #[serde(with = "clickhouse::serde::chrono::datetime64::secs")]
      dt64s_chrono: DateTime<Utc>,  // `DateTime64(0)`
      #[serde(with = "clickhouse::serde::chrono::datetime64::millis")]
      dt64ms_chrono: DateTime<Utc>, // `DateTime64(3)`
      #[serde(with = "clickhouse::serde::chrono::datetime64::micros")]
      dt64us_chrono: DateTime<Utc>, // `DateTime64(6)`
      #[serde(with = "clickhouse::serde::chrono::datetime64::nanos")]
      dt64ns_chrono: DateTime<Utc>, // `DateTime64(9)`
  }
  

• Tuple(A, B, ...) maps to/from (A, B, ...) or a newtype around it.

• Array(_) maps to/from any slice, e.g. Vec<_>, &[_]. Newtypes are also supported.

• Map(K, V) can be deserialized as HashMap<K, V> or Vec<(K, V)>.

• LowCardinality(_) is supported seamlessly.

• Nullable(_) maps to/from Option<_>. For clickhouse::serde::* helpers add ::option.

  Example

  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      #[serde(with = "clickhouse::serde::ipv4::option")]
      ipv4_opt: Option<Ipv4Addr>,
  }

• Nested is supported by providing multiple arrays with renaming.

  Example

  // CREATE TABLE test(items Nested(name String, count UInt32))
  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      #[serde(rename = "items.name")]
      items_name: Vec<String>,
      #[serde(rename = "items.count")]
      items_count: Vec<u32>,
  }

• Geo types are supported. Point behaves like a tuple (f64, f64), and the rest of the types are just slices of points.

  Example

  type Point = (f64, f64);
  type Ring = Vec<Point>;
  type Polygon = Vec<Ring>;
  type MultiPolygon = Vec<Polygon>;
  type LineString = Vec<Point>;
  type MultiLineString = Vec<LineString>;
  
  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      point: Point,
      ring: Ring,
      polygon: Polygon,
      multi_polygon: MultiPolygon,
      line_string: LineString,
      multi_line_string: MultiLineString,
  }

• Variant data type is supported as a Rust enum. As the inner Variant types are always sorted alphabetically, Rust enum variants should be defined in the exactly same order as it is in the data type; their names are irrelevant, only the order of the types matters. This following example has a column defined as Variant(Array(UInt16), Bool, Date, String, UInt32):

  Example

  #[derive(Serialize, Deserialize)]
  enum MyRowVariant {
      Array(Vec<i16>),
      Boolean(bool),
      #[serde(with = "clickhouse::serde::time::date")]
      Date(time::Date),
      String(String),
      UInt32(u32),
  }
  
  #[derive(Row, Serialize, Deserialize)]
  struct MyRow {
      id: u64,
      var: MyRowVariant,
  }

• New JSON data type is currently supported as a string when using ClickHouse 24.10+. See this example for more details.

• Dynamic data type is not supported for now.

See also the additional examples:

• Simpler ClickHouse data types
• Container-like ClickHouse data types
• Variant data type

The crate provides utils for mocking CH server and testing DDL, SELECT and INSERT queries.

The functionality can be enabled with the test-util feature. Use it only in dev-dependencies.

See the example.