使用 pyspark 建立连接以钻取

Question

我正在尝试使用 drill to connect in pyspark shell 将数据从 MapR DB 提取到数据框中。

这是我在 pyspark 中所做的 shell :

 `dataframe_mysql = sqlContext.read.format("jdbc").option("url", "jdbc:drill:zk=localhost:5181/drill/demo_mapr_com-drillbits;schema=dfs;").option("driver","org.apache.drill.jdbc.Driver").option("dbtable","select * from dfs.`/DDDE/jsondb/ruleengine/testtransactions").option("user","root").option("password","mapr").load()`

不幸的是，我收到以下错误。

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/mapr/spark/spark-1.6.3-bin-hadoop2.6/python/pyspark/sql/readwriter.py", line 139, in load
    return self._df(self._jreader.load())
  File "/opt/mapr/spark/spark-1.6.3-bin-hadoop2.6/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py", line 813, in __call__
  File "/opt/mapr/spark/spark-1.6.3-bin-hadoop2.6/python/pyspark/sql/utils.py", line 45, in deco
    return f(*a, **kw)
  File "/opt/mapr/spark/spark-1.6.3-bin-hadoop2.6/python/lib/py4j-0.9-src.zip/py4j/protocol.py", line 308, in get_return_value
py4j.protocol.Py4JJavaError: An error occurred while calling o88.load.
: java.lang.ClassNotFoundException: org.apache.drill.jdbc.Driver
        at java.net.URLClassLoader.run(URLClassLoader.java:366)
        at java.net.URLClassLoader.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at org.apache.spark.sql.execution.datasources.jdbc.DriverRegistry$.register(DriverRegistry.scala:38)
        at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory.apply(JdbcUtils.scala:45)
        at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory.apply(JdbcUtils.scala:45)
        at scala.Option.foreach(Option.scala:236)
        at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$.createConnectionFactory(JdbcUtils.scala:45)
        at org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD$.resolveTable(JDBCRDD.scala:120)
        at org.apache.spark.sql.execution.datasources.jdbc.JDBCRelation.<init>(JDBCRelation.scala:91)
        at org.apache.spark.sql.execution.datasources.jdbc.DefaultSource.createRelation(DefaultSource.scala:57)
        at org.apache.spark.sql.execution.datasources.ResolvedDataSource$.apply(ResolvedDataSource.scala:158)
        at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:119)
        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:606)
        at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231)
        at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:381)
        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:209)
        at java.lang.Thread.run(Thread.java:745

知道我哪里出错了吗？

编辑：在 sqlline 中，我可以通过以下方式检索数据框：

!connect jdbc:drill:zk=localhost:31010/drill/demo_mapr_com-drillbits;schema=dfs;
!connect jdbc:drill:zk=localhost:5181/drill/demo_mapr_com-drillbits;schema=dfs;
select * from dfs.`/DDDE/jsondb/ruleengine/testtransactions`;

Answer 1

Drill JDBC 驱动程序 JAR 文件必须存在于客户端计算机上，以便您可以为要使用的应用程序或第三方工具配置驱动程序。您可以通过以下方式获取驱动程序：

将 drill-jdbc-all JAR 文件从以下 Drill 安装目录复制到您的工作目录，然后按照以下步骤启动您的脚本：

./bin/spark-submit --jars drill-jdbc-all-<version>.jar your_spark_script.py

如果您正在使用 pyspark，您应该执行以下操作：

pyspark --jars drill-jdbc-all-<version>.jar

如果找不到JAR，在你的drill目录安装：

$> tree jars/jdbc-driver/
jars/jdbc-driver/
 └── drill-jdbc-all-1.10.0.jar # this is it

Answer 2

使用 Drill ODBC 驱动程序 jar 文件的替代方法是使用 Drill RESTful API，如下所述：https://drill.apache.org/docs/rest-api-introduction/#query

使用 pyspark 建立连接以钻取

Establishing connection to drill using pyspark

apache-spark

pyspark

pyspark-sql

apache-drill

mapr