Crate scylla

Expand description

Async Rust driver for the Scylla database written in Rust. Although optimized for Scylla, the driver is also compatible with Apache Cassandra®.

Documentation book

The best source to learn about this driver is the documentation book.
This page contains mainly API documentation

Driver overview

Connecting

All driver activity revolves around the Session
Session is created by specifying a few known nodes and connecting to them:

use scylla::{Session, SessionBuilder};
use std::error::Error;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
   let session: Session = SessionBuilder::new()
        .known_node("127.0.0.1:9042")
        .known_node("1.2.3.4:9876")
        .build()
        .await?;

   Ok(())
}

Session is usually created using the SessionBuilder.
All configuration options for a Session can be specified while building.

Making queries

After successfully connecting to the cluster we can make queries.
The driver supports multiple query types:

Simple
Simple paged
Prepare (need to be prepared before use)
Prepared paged
Batch

To specify options for a single query create the query object and configure it:

For simple: Query
For prepared: PreparedStatement
For batch: Batch

The easiest way to specify bound values in a query is using a tuple:

// Insert an int and text into the table
session
    .query(
        "INSERT INTO ks.tab (a, b) VALUES(?, ?)",
        (2_i32, "some text")
    )
    .await?;

But the driver will accept anything implementing the trait ValueList

Receiving results

The easiest way to read rows returned by a query is to cast each row to a tuple of values:

use scylla::IntoTypedRows;

// Read rows containing an int and text
let rows_opt = session
.query("SELECT a, b FROM ks.tab", &[])
    .await?
    .rows;

if let Some(rows) = rows_opt {
    for row in rows.into_typed::<(i32, String)>() {
        // Parse row as int and text \
        let (int_val, text_val): (i32, String) = row?;
    }
}