PySpark sqlContext读取Postgres 9.6 NullPointerException [英] PySpark sqlContext read Postgres 9.6 NullPointerException
问题描述
尝试使用Postgres DB中的PySpark读取表。我设置了以下代码并验证了SparkContext的存在:
Trying to read a table with PySpark from a Postgres DB. I have set up the following code and verified SparkContext exists:
import os
os.environ['PYSPARK_SUBMIT_ARGS'] = '--driver-class-path /tmp/jars/postgresql-42.0.0.jar --jars /tmp/jars/postgresql-42.0.0.jar pyspark-shell'
from pyspark import SparkContext, SparkConf
conf = SparkConf()
conf.setMaster("local[*]")
conf.setAppName('pyspark')
sc = SparkContext(conf=conf)
from pyspark.sql import SQLContext
properties = {
"driver": "org.postgresql.Driver"
}
url = 'jdbc:postgresql://tom:@localhost/gqp'
sqlContext = SQLContext(sc)
sqlContext.read \
.format("jdbc") \
.option("url", url) \
.option("driver", properties["driver"]) \
.option("dbtable", "specimen") \
.load()
我收到以下错误:
Py4JJavaError: An error occurred while calling o812.load. : java.lang.NullPointerException
我的数据库名称为 gqp
,表为标本
,并已使用Postgres.app macOS验证其是否在 localhost
上运行应用程序。
The name of my database is gqp
, table is specimen
, and have verified it is running on localhost
using the Postgres.app macOS app.
推荐答案
URL出了问题!
最初是: url ='jdbc:postgresql:// tom:@ localhost / gqp'
我删除了 tom:@
部分,它起作用了。 URL必须遵循以下格式: jdbc:postgresql:// ip_address:port / db_name
,而mine是直接从Flask项目复制的。
I removed the tom:@
part, and it worked. The URL must follow the pattern: jdbc:postgresql://ip_address:port/db_name
, whereas mine was directly copied from a Flask project.
如果您正在阅读本文,希望您不要犯同样的错误:)
If you're reading this, hope you didn't make this same mistake :)
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