如何通过 amazon workspace 中的 EMR jupyter lab notebook 读取 postgres DB 表

Question

我正在尝试从 postgres 表中读取表。 但我面临以下错误。 注意：我无法从本地引用外部文件，因为它是一个私有工作区。

JDBC：例如：

"url":"jdbc:postgresql://xxxx-xxxxx-postgresql-prod01.cluster-xxxx.xx-xx-1.rds.amazonaws.com:0000/db_xxx_txxx",

错误我越来越喜欢：“

java.lang.ClassNotFoundException: org.postgresql.Driver

“

An error was encountered:
An error occurred while calling o153.jdbc.
: java.lang.ClassNotFoundException: org.postgresql.Driver
    at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
    at org.apache.spark.sql.execution.datasources.jdbc.DriverRegistry$.register(DriverRegistry.scala:46)
    at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.$anonfun$driverClass$1(JDBCOptions.scala:102)
    at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.$anonfun$driverClass$1$adapted(JDBCOptions.scala:102)
    at scala.Option.foreach(Option.scala:407)
    at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.<init>(JDBCOptions.scala:102)
    at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.<init>(JDBCOptions.scala:38)
    at org.apache.spark.sql.execution.datasources.jdbc.JdbcRelationProvider.createRelation(JdbcRelationProvider.scala:32)
    at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:355)
    at org.apache.spark.sql.DataFrameReader.loadV1Source(DataFrameReader.scala:325)
    at org.apache.spark.sql.DataFrameReader.$anonfun$load$3(DataFrameReader.scala:307)
    at scala.Option.getOrElse(Option.scala:189)
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:307)
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:225)
    at org.apache.spark.sql.DataFrameReader.jdbc(DataFrameReader.scala:340)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
    at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
    at py4j.Gateway.invoke(Gateway.java:282)
    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
    at py4j.commands.CallCommand.execute(CallCommand.java:79)
    at py4j.GatewayConnection.run(GatewayConnection.java:238)
    at java.lang.Thread.run(Thread.java:750)

我试过下面的代码。

tables = read_table(
    url=URL,
    table="information_schema.tables",
    driver=DRIVER,
    user=USER,
    password=PASS
)

Answer 1

您需要先将 Postgres 驱动程序添加为依赖项/类路径。

首先将 JAR 复制到集群或 s3 上，然后在第一个单元格中执行：

%%configure -f
{ "conf":{
          "spark.jars": "s3://JAR-LOCATION/postgresql.jar"
         }
}

参考 带有 EMR 和 Jupyter 笔记本的 Postgres JAR

或者，您可以在创建 SparkSession 时配置它。

spark = SparkSession.builder.config('spark.driver.extraClassPath', '/JAR-LOCATION/postgresql.jar').getOrCreate()

更新：根据你的评论，因为你不能推送 JAR，你可以使用 maven 依赖

%%configure -f
{
    "conf": {"spark.jars.packages": "org.postgresql:postgresql:jar:42.4.3"}
}