pgx - PostgreSQL Driver and Toolkit

This is the v5 development branch. It is still in active development and testing.

pgx is a pure Go driver and toolkit for PostgreSQL.

pgx aims to be low-level, fast, and performant, while also enabling PostgreSQL-specific features that the standard database/sql package does not allow for.

The driver component of pgx can be used alongside the standard database/sql package.

The toolkit component is a related set of packages that implement PostgreSQL functionality such as parsing the wire protocol and type mapping between PostgreSQL and Go. These underlying packages can be used to implement alternative drivers, proxies, load balancers, logical replication clients, etc.

Example Usage

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/jackc/pgx/v5"
)

func main() {
	// urlExample := "postgres://username:password@localhost:5432/database_name"
	conn, err := pgx.Connect(context.Background(), os.Getenv("DATABASE_URL"))
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to connect to database: %v\n", err)
		os.Exit(1)
	}
	defer conn.Close(context.Background())

	var name string
	var weight int64
	err = conn.QueryRow(context.Background(), "select name, weight from widgets where id=$1", 42).Scan(&name, &weight)
	if err != nil {
		fmt.Fprintf(os.Stderr, "QueryRow failed: %v\n", err)
		os.Exit(1)
	}

	fmt.Println(name, weight)
}

See the getting started guide for more information.

Choosing Between the pgx and database/sql Interfaces

It is recommended to use the pgx interface if:

1. The application only targets PostgreSQL.
2. No other libraries that require database/sql are in use.

The pgx interface is faster and exposes more features.

The database/sql interface only allows the underlying driver to return or receive the following types: int64, float64, bool, []byte, string, time.Time, or nil. Handling other types requires implementing the database/sql.Scanner and the database/sql/driver/driver.Valuer interfaces which require transmission of values in text format. The binary format can be substantially faster, which is what the pgx interface uses.

Features

pgx supports many features beyond what is available through database/sql:

• Support for approximately 70 different PostgreSQL types
• Automatic statement preparation and caching
• Batch queries
• Single-round trip query mode
• Full TLS connection control
• Binary format support for custom types (allows for much quicker encoding/decoding)
• COPY protocol support for faster bulk data loads
• Extendable logging support
• Connection pool with after-connect hook for arbitrary connection setup
• Listen / notify
• Conversion of PostgreSQL arrays to Go slice mappings for integers, floats, and strings
• Hstore support
• JSON and JSONB support
• Maps inet and cidr PostgreSQL types to net.IPNet and net.IP
• Large object support
• NULL mapping to Null* struct or pointer to pointer
• Supports database/sql.Scanner and database/sql/driver.Valuer interfaces for custom types
• Notice response handling
• Simulated nested transactions with savepoints

Performance

There are three areas in particular where pgx can provide a significant performance advantage over the standard database/sql interface and other drivers:

1. PostgreSQL specific types - Types such as arrays can be parsed much quicker because pgx uses the binary format.
2. Automatic statement preparation and caching - pgx will prepare and cache statements by default. This can provide an significant free improvement to code that does not explicitly use prepared statements. Under certain workloads, it can perform nearly 3x the number of queries per second.
3. Batched queries - Multiple queries can be batched together to minimize network round trips.

Testing

pgx tests naturally require a PostgreSQL database. It will connect to the database specified in the PGX_TEST_DATABASE environment variable. The PGX_TEST_DATABASE environment variable can either be a URL or DSN. In addition, the standard PG* environment variables will be respected. Consider using direnv to simplify environment variable handling.

Example Test Environment

Connect to your PostgreSQL server and run:

create database pgx_test;

Connect to the newly-created database and run:

create domain uint64 as numeric(20,0);

Now, you can run the tests:

PGX_TEST_DATABASE="host=/var/run/postgresql database=pgx_test" go test ./...

In addition, there are tests specific for PgBouncer that will be executed if PGX_TEST_PGBOUNCER_CONN_STRING is set.

Supported Go and PostgreSQL Versions

pgx supports the same versions of Go and PostgreSQL that are supported by their respective teams. For Go that is the two most recent major releases and for PostgreSQL the major releases in the last 5 years. This means pgx supports Go 1.17 and higher and PostgreSQL 10 and higher. pgx also is tested against the latest version of CockroachDB.

v5 is targeted at Go 1.18+. The general release of v5 is not planned until second half of 2022 so it is expected that the policy of supporting the two most recent versions of Go will be maintained or restored soon after its release.

Version Policy

pgx follows semantic versioning for the documented public API on stable releases. v4 is the latest stable major version.

PGX Family Libraries

github.com/jackc/pglogrepl

pglogrepl provides functionality to act as a client for PostgreSQL logical replication.

github.com/jackc/pgmock

pgmock offers the ability to create a server that mocks the PostgreSQL wire protocol. This is used internally to test pgx by purposely inducing unusual errors. pgproto3 and pgmock together provide most of the foundational tooling required to implement a PostgreSQL proxy or MitM (such as for a custom connection pooler).

github.com/jackc/tern

tern is a stand-alone SQL migration system.

github.com/jackc/pgerrcode

pgerrcode contains constants for the PostgreSQL error codes.

Adapters for 3rd Party Types

• github.com/jackc/pgx-gofrs-uuid
• github.com/jackc/pgx-shopspring-decimal
• github.com/vgarvardt/pgx-google-uuid

Adapters for 3rd Party Loggers

• github.com/jackc/pgx-go-kit-log
• github.com/jackc/pgx-log15
• github.com/jackc/pgx-logrus
• github.com/jackc/pgx-zap
• github.com/jackc/pgx-zerolog

3rd Party Libraries with PGX Support

github.com/georgysavva/scany

Library for scanning data from a database into Go structs and more.

https://github.com/otan/gopgkrb5

Adds GSSAPI / Kerberos authentication support.