Connecting Spark to HAWQ via JDBC driver

Refresh

November 2018

Views

1.3k time

3

Trying to connect to HAWQ from Spark, using greenplum's odbc/jdbc drivers (downloaded from the proper Pivotal page).

Using Spark 1.4, here's the sample code written in python: (All capitals have proper variable assignments) ...

from pyspark import SparkContext
from pyspark.sql import SQLContext


sc = SparkContext()
sqlContext = SQLContext(sc)

df = sqlContext.read.load(source='jdbc',\
                      url='IP_ADDRESS:PORT/DB_NAME?user=USERNAME&password=PASSWORD&ssl=true',\
                      dbtable='SCHEMA.TABLE_NAME')

...

Spark submit command appends the odbc driver to the classpath. I've done a 'hello world' with the basic sqlContext instantiation and everything runs fine on the cluster. But when I try to actually connect to the HAWQ postgresql db it will not run.

Error:

py4j.protocol.Py4JJavaError: An error occurred while calling o24.load.
: java.util.NoSuchElementException: key not found: path
        at scala.collection.MapLike$class.default(MapLike.scala:228)
        at org.apache.spark.sql.sources.CaseInsensitiveMap.default(ddl.scala:467)
        at scala.collection.MapLike$class.apply(MapLike.scala:141)
        at org.apache.spark.sql.sources.CaseInsensitiveMap.apply(ddl.scala:467)
        at org.apache.spark.sql.sources.ResolvedDataSource$.apply(ddl.scala:273)
        at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:114)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231)
        at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:379)
        at py4j.Gateway.invoke(Gateway.java:259)
        at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:133)
        at py4j.commands.CallCommand.execute(CallCommand.java:79)
        at py4j.GatewayConnection.run(GatewayConnection.java:207)
        at java.lang.Thread.run(Thread.java:722)

Any thoughts or suggestions? I've tried at least 20 combinations of the "df = sqlContext.read.load..." definition but to no avail.

1 answers

4

Правильный формат для JDBC должно быть что-то вроде этого

df = sqlContext.read.format('jdbc').options(url='jdbc:postgresql://node1:5432/postgres?user=myuser&password=password',dbtable='test').load()

Другой пример здесь http://spark.apache.org/docs/latest/sql-programming-guide.html#jdbc-to-other-databases