Using pyspark to connect to PostgreSQL

Question

I am trying to connect to a database with pyspark and I am using the following code:

sqlctx = SQLContext(sc)
df = sqlctx.load(
    url = "jdbc:postgresql         


        

Answer 1

I had trouble to get a connection to the postgresDB with the jars i had on my computer. This code solved my problem with the driver

 from pyspark.sql import SparkSession
 import os

 sparkClassPath = os.environ['PYSPARK_SUBMIT_ARGS'] = '--packages org.postgresql:postgresql:42.1.1 pyspark-shell'

 spark = SparkSession \
    .builder \
    .config("spark.driver.extraClassPath", sparkClassPath) \
    .getOrCreate()

 df = spark.read \
    .format("jdbc") \
    .option("url", "jdbc:postgresql://localhost:5432/yourDBname") \
    .option("driver", "org.postgresql.Driver") \
    .option("dbtable", "yourtablename") \
    .option("user", "postgres") \
    .option("password", "***") \
    .load()

df.show()

Answer 2

Just initialize pyspark with --jars <path/to/your/jdbc.jar>

E.g.: pyspark --jars /path/Downloads/postgresql-42.2.16.jar

then create a dataframe as suggested above in other answers

E.g.:

df2 = spark.read.format("jdbc").option("url", "jdbc:postgresql://localhost:5432/db").option("dbtable", "yourTableHere").option("user", "postgres").option("password", "postgres").option("driver", "org.postgresql.Driver").load()

Answer 3

and i also meat this error

java.sql.SQLException: No suitable driver
 at java.sql.DriverManager.getDriver(Unknown Source)

and add one item .config('spark.driver.extraClassPath', './postgresql-42.2.18.jar') in SparkSession is fine and worked. like

from pyspark import SparkContext, SparkConf
import os
from pyspark.sql.session import SparkSession

spark = SparkSession \
    .builder \
    .appName('Python Spark Postgresql') \
    .config("spark.jars", "./postgresql-42.2.18.jar") \
    .config('spark.driver.extraClassPath', './postgresql-42.2.18.jar') \
    .getOrCreate()


df = spark.read \
    .format("jdbc") \
    .option("url", "jdbc:postgresql://localhost:5432/abc") \
    .option("dbtable", 'tablename') \
    .option("user", "postgres") \
    .option("password", "1") \
    .load()

df.printSchema()

Answer 4

Download the PostgreSQL JDBC Driver from https://jdbc.postgresql.org/download.html

Then replace the database configuration values by yours.

from pyspark.sql import SparkSession

spark = SparkSession \
    .builder \
    .appName("Python Spark SQL basic example") \
    .config("spark.jars", "/path_to_postgresDriver/postgresql-42.2.5.jar") \
    .getOrCreate()

df = spark.read \
    .format("jdbc") \
    .option("url", "jdbc:postgresql://localhost:5432/databasename") \
    .option("dbtable", "tablename") \
    .option("user", "username") \
    .option("password", "password") \
    .option("driver", "org.postgresql.Driver") \
    .load()

df.printSchema()

More info: https://spark.apache.org/docs/latest/sql-data-sources-jdbc.html