package main

import (
  "context"
  "os"

  "github.com/jackc/pgx/v5"
  "github.com/jackc/pgx/v5/pgxpool"
  pgxDecimal "github.com/ColeBurch/pgx-govalues-decimal"
)

func main() {
  pgxConfig, err := pgxpool.ParseConfig(os.Getenv("PG_URI"))
  if err != nil {
    panic(err)
  }

  pgxConfig.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
    pgxDecimal.Register(conn.TypeMap())
    return nil
  }

  pgxConnPool, err := pgxpool.NewWithConfig(context.TODO(), pgxConfig)
  if err != nil {
    panic(err)
  }

  // use pgxConnPool
  ...
}