spark = SparkSession.builder.config(conf=spark_conf).getOrCreate()
#make sure the necessary jar files are loaded
#@ opt/spark/jars folder
df = spark.read
.format("jdbc")
.option("url", "jdbc:postgresql://<host>:<port>/<db_name>")
.option("dbtable", "<schema>.<tablename>")
.option("user", "<username>")
.option("password", "<password>")
.option("driver", "org.postgresql.Driver")
.load()