Rust¶
Connect to CrateDB from Rust applications.
About
postgres is a synchronous Rust client for the PostgreSQL database. r2d2 is a generic connection pool for Rust.
Synopsis (localhost)
src/main.rs
use postgres::{Client, NoTls};
fn main() -> Result<(), Box<dyn std::error::Error>> {
// Connect to database.
let mut client = Client::connect("postgresql://crate@localhost:5432/?sslmode=disable", NoTls)?;
// Invoke query and display results.
for row in client.query(
"SELECT mountain, height FROM sys.summits ORDER BY height DESC LIMIT 3",
&[],
)? {
let mountain: &str = row.get(0);
let height: i32 = row.get(1);
println!("{}: {}", mountain, height);
}
Ok(())
}
Add the code into the file src/main.rs after running cargo init.
Start CrateDB using Docker or Podman, then invoke the example program.
docker run --rm --publish=5432:5432 docker.io/crate '-Cdiscovery.type=single-node'
cargo init
cargo add postgres
cargo run
SSL connection
Add TLS support, and replace username, password, and hostname with values matching your environment. Also use this variant to connect to CrateDB Cloud.
src/main.rs
use postgres::Client;
use native_tls::TlsConnector;
use postgres_native_tls::MakeTlsConnector;
fn main() -> Result<(), Box<dyn std::error::Error>> {
// Connect to database.
let tls = MakeTlsConnector::new(TlsConnector::new()?);
let mut client = Client::connect("postgresql://admin:password@testcluster.cratedb.net:5432/?sslmode=require", tls)?;
// Invoke query and display results.
for row in client.query(
"SELECT mountain, height FROM sys.summits ORDER BY height DESC LIMIT 3",
&[],
)? {
let mountain: &str = row.get(0);
let height: i32 = row.get(1);
println!("{}: {}", mountain, height);
}
Ok(())
}
Add the code into the file src/main.rs after running cargo init.
Start CrateDB using Docker or Podman, then invoke the example program.
docker run --rm --publish=5432:5432 docker.io/crate '-Cdiscovery.type=single-node'
cargo init
cargo add postgres postgres-native-tls native-tls
cargo run
Synopsis (connection pool)
src/main.rs
use postgres::{NoTls, Row};
use r2d2_postgres::{
r2d2::{Pool},
PostgresConnectionManager,
};
fn main() -> Result<(), Box<dyn std::error::Error>> {
// Connect to database.
let pg_manager = PostgresConnectionManager::new(
"postgresql://crate:crate@localhost:5432/?sslmode=disable"
.parse()
.unwrap(),
NoTls,
);
let pg_pool = Pool::builder()
.max_size(5)
.build(pg_manager)
.expect("Postgres pool failed");
let mut pg_conn = pg_pool.get().unwrap();
// Invoke query.
let result = pg_conn.query("SELECT mountain, height FROM sys.summits ORDER BY height DESC LIMIT 3", &[]);
let rows = result.unwrap().into_iter().collect::<Vec<Row>>();
// Display results.
for row in rows {
let mountain: &str = row.get(0);
let height: i32 = row.get(1);
println!("{}: {}", mountain, height);
}
Ok(())
}
Add the code into the file src/main.rs after running cargo init.
Start CrateDB using Docker or Podman, then invoke the example program.
docker run --rm --publish=5432:5432 docker.io/crate '-Cdiscovery.type=single-node'
cargo init
cargo add postgres r2d2_postgres
cargo run
Example¶
Connecting to CrateDB with Rust.