PGX Smart Driver

YugabyteDB PGX smart driver is a Go driver for YSQL based on PGX, with additional connection load balancing features.

For more information on the YugabyteDB PGX smart driver, see the following:

• YugabyteDB smart drivers for YSQL
• CRUD operations
• GitHub repository
• Smart Driver architecture

Import the driver package

You can import the YugabyteDB PGX driver package by adding the following import statement in your Go code.

import (
  "github.com/yugabyte/pgx/v5"
)

Optionally, you can choose to import the pgxpool package instead. Refer to Using pgxpool API to learn more.

Fundamentals

Learn how to perform common tasks required for Go application development using the YugabyteDB PGX driver.

Load balancing connection properties

The following connection properties need to be added to enable load balancing:

• load_balance - enable cluster-aware load balancing by setting this property to one of the allowed values other than false; disabled by default.
• topology_keys - provide comma-separated geo-location values to enable topology-aware load balancing. Geo-locations can be provided as cloud.region.zone. Specify all zones in a region as cloud.region.*. To designate fallback locations for when the primary location is unreachable, specify a priority in the form :n, where n is the order of precedence. For example, cloud1.datacenter1.rack1:1,cloud1.datacenter1.rack2:2.

By default, the driver refreshes the list of nodes every 300 seconds (5 minutes). You can change this value by including the yb_servers_refresh_interval connection parameter.

For more information, see Cluster-aware load balancing.

Use the driver

To use the driver, pass new connection properties for load balancing in the connection URL or properties pool.

To enable uniform load balancing across all servers, you set the load_balance property to true or any in the URL, as per the following example:

baseUrl := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
                  user, password, host, port, dbname)
url := fmt.Sprintf("%s?load_balance=true", baseUrl)
conn, err := pgx.Connect(context.Background(), url)

You can specify multiple hosts in the connection string in case the primary address fails. After the driver establishes the initial connection, it fetches the list of available servers from the universe, and performs load balancing of subsequent connection requests across these servers.

To specify topology keys, you set the topology_keys property to comma separated values, as per the following example:

baseUrl := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
                  user, password, host, port, dbname)
url = fmt.Sprintf("%s?load_balance=true&topology_keys=cloud1.datacenter1.rack1", baseUrl)
conn, err := pgx.Connect(context.Background(), url)

Create table

Tables can be created in YugabyteDB by passing the CREATE TABLE DDL statement to the Exec() function on the conninstance.

CREATE TABLE employee (id int PRIMARY KEY, name varchar, age int, language varchar)

var createStmt = 'CREATE TABLE employee (id int PRIMARY KEY,
                  name varchar, age int, language varchar)';
_, err = conn.Exec(context.Background(), createStmt)
if err != nil {
  fmt.Fprintf(os.Stderr, "Exec for create table failed: %v\n", err)
}

The conn.Exec() function also returns an error object which, if not nil, needs to be handled in your code.

Read more on designing Database schemas and tables.

Read and write data

Insert data

To write data into YugabyteDB, execute the INSERT statement using the same conn.Exec() function.

INSERT INTO employee(id, name, age, language) VALUES (1, 'John', 35, 'Go')

var insertStmt string = "INSERT INTO employee(id, name, age, language)" +
                        " VALUES (1, 'John', 35, 'Go')";
_, err = conn.Exec(context.Background(), insertStmt)
if err != nil {
  fmt.Fprintf(os.Stderr, "Exec for create table failed: %v\n", err)
}

By default, the YugabyteDB PGX driver automatically prepares and caches statements.

Query data

To query data from YugabyteDB tables, execute the SELECT statement using the function conn.Query().

Query results are returned in pgx.Rows, which can be iterated using the pgx.Rows.next() method.

Then read the data using pgx.rows.Scan().

The SELECT DML statement:

SELECT * from employee;

Code snippet:

var name string
var age int
var language string

rows, err := conn.Query(context.Background(), "SELECT name, age, language FROM employee WHERE id = 1")
if err != nil {
  log.Fatal(err)
}
defer rows.Close()

fmt.Printf("Query for id=1 returned: ");
for rows.Next() {
  err := rows.Scan(&name, &age, &language)
  if err != nil {
    log.Fatal(err)
  }
  fmt.Printf("Row[%s, %d, %s]\n", name, age, language)
}

err = rows.Err()
if err != nil {
  log.Fatal(err)
}

Use pgxpool API

The YugabyteDB PGX driver also provides pool APIs via the pgxpool package. You can import it as follows:

import (
  "github.com/yugabyte/pgx/v5/pgxpool"
)

Establish a connection

The primary way of establishing a connection is with pgxpool.New().

pool, err := pgxpool.New(context.Background(), os.Getenv("DATABASE_URL"))

You can also provide configuration for the pool as follows:

config, err := pgxpool.ParseConfig(os.Getenv("DATABASE_URL"))
if err != nil {
    // ...
}
config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
    // do something with every new connection
}

pool, err := pgxpool.NewWithConfig(context.Background(), config)

You can either Acquire a connection from the pool and execute queries on it, or use the Query API to directly execute SQLs on the pool.

conn, err := pool.Acquire(context.Background())
if err != nil {
  fmt.Fprintf(os.Stderr, "Unable to connect to database: %v\n", err)
  os.Exit(1)
}
defer conn.Release()

var createStmt = `CREATE TABLE employee (id int PRIMARY KEY,
                  name varchar, age int, language varchar)`
_, err = conn.Exec(context.Background(), createStmt)

// ...

rows, err := pool.Query(context.Background(), "SELECT name, age, language FROM employee WHERE id = 1")

For more details, see the pgxpool package documentation.

Configure SSL/TLS

To build a Go application that communicates securely over SSL with YugabyteDB database, you need the root certificate (ca.crt) of the YugabyteDB cluster. To generate these certificates and install them while launching the cluster, follow the instructions in Create server certificates.

Because a YugabyteDB Aeon cluster is always configured with SSL/TLS, you don't have to generate any certificate but only set the client-side SSL configuration. To fetch your root certificate, refer to CA certificate.

For a YugabyteDB Aeon cluster, or a YugabyteDB cluster with SSL/TLS enabled, set the SSL-related environment variables as follows at the client side.

$ export PGSSLMODE=verify-ca
$ export PGSSLROOTCERT=~/root.crt  # Here, the CA certificate file is downloaded as `root.crt` under home directory. Modify your path accordingly.

SSL modes

Transaction and isolation levels

YugabyteDB supports transactions for inserting and querying data from the tables. YugabyteDB supports different isolation levels for maintaining strong consistency for concurrent data access.

The PGX driver provides the conn.Begin() function to start a transaction. The conn.BeginEx() function can create a transaction with a specified isolation level.

tx, err := conn.Begin()
if err != nil {
    return err
}
defer tx.Rollback()

_, err = tx.Exec("insert into employee(id, name, age, language) values (1, 'John', 35, 'Go')")
if err != nil {
    return err
}

err = tx.Commit()
if err != nil {
    return err
}