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Connect an application

• YSQL

• YugabyteDB Rust-Postgres Smart Driver

The YugabyteDB Rust-Postgres Smart Driver is a rust driver for YSQL built on the PostgreSQL rust-postgres driver, with additional connection load balancing features.

CRUD operations

The following sections demonstrate how to perform common tasks required for Rust application development using the YugabyteDB Rust smart driver.

To start building your application, make sure you have met the prerequisites.

Step 1: Set up the database connection

The following table describes the connection parameters required to connect, including smart driver parameters for uniform and topology load balancing.

The following is an example connection string for connecting to YugabyteDB:

postgresql://127.0.0.1:5433/yugabyte?user=yugabyte&password=yugabyte& \
    yb_servers_refresh_interval=0& \
    load_balance=true& \
    topology_keys=cloud1.datacenter1.rack2

After the driver establishes the initial connection, it fetches the list of available servers from the cluster, and load-balances subsequent connection requests across these servers.

Use multiple addresses

You can specify multiple hosts in the connection string to provide alternative options during the initial connection in case the primary address fails.

Delimit the addresses using commas, as follows:

postgresql://127.0.0.1:5433,127.0.0.2:5433/yugabyte?user=yugabyte&password=yugabyte& \
    yb_servers_refresh_interval=0& \
    load_balance=true& \
    topology_keys=cloud1.datacenter1.rack2&fallback_to_topology_keys_only=true

The hosts are only used during the initial connection attempt. If the first host is down when the driver is connecting, the driver attempts to connect to the next host in the string, and so on.

Step 2: Write your application

Make sure that you have created a new rust project as part of the prerequisites.

1. Add yb-postgres = "0.19.7-yb-1-beta dependency in the Cargo.toml file as follows:

   [package]
   name = "HelloWorld-rust"
   version = "0.1.0"
   edition = "2021"
   
   # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
   
   [dependencies]
   yb-postgres = "0.19.7-yb-1-beta"
   

2. Replace the existing code in src/main.rs with the following sample code to set up tables and query the table contents. Replace the values in the connection string connection_url with the database credentials, if required.

   use yb_postgres::{Client, NoTls, Error};
   fn main() -> Result<(), Error> {
   
       let connection_url: String = String::from("postgresql://127.0.0.1:5433/yugabyte?user=yugabyte&password=yugabyte&load_balance=true");
   
       //creating connection to YugabyteDB cluster
       let mut client=Client::connect(&connection_url,NoTls,)?;
       println!("Connected to the YugabyteDB Cluster successfully.");
   
       client.execute("DROP TABLE IF EXISTS employee", &[])?;
       client.execute("CREATE TABLE IF NOT EXISTS employee (id int primary key, name varchar, age int, language text)", &[])?;
       println!("Created table employee");
   
       client.execute("INSERT INTO employee VALUES (1, 'John', 35, 'Java')", &[])?;
       println!("Inserted employee 1");
   
       client.execute("INSERT INTO employee VALUES (2, 'Sam', 37, 'JavaScript')", &[])?;
       println!("Inserted employee 2");
   
       println!("Employees Information:");
       for row in client.query("select * from employee", &[])? {
           let id: i32 = row.get(0);
           let name: String = row.get(1);
           let age: i32 = row.get(2);
           let language: String = row.get(3);
           println!("{}. name = {}, age = {}, language = {}",id, name,age,language);
       }
   
       //closing the connection
       let _ = client.close();
   
       Ok(())
   }
   

3. Run the HelloWorld-rust application using the following command:

   cargo run
   

   You should see output similar to the following:

   Created table employee
   Inserted employee 1
   Inserted employee 2
   Employees Information:
   1. name = John, age = 35, language = Java
   2. name = Sam, age = 37, language = JavaScript
   

   If there is no output or you get an error, verify the parameters included in the connection string.