我是MacOS用户，我刚刚下载了Apache Spark。然后我把它放在/usr/local/spark. 这是我.bash_profile里面的内容：
export SPARK_HOME="/usr/local/spark"
export PYSPARK_PYTHON=python3
export PATH=$PATH:$SPARK_HOME/bin
#export PYSPARK_DRIVER_PYTHON="jupyter"
#export PYSPARK_DRIVER_PYTHON_OPTS="notebook"
问题是，当键入 pyspark 进入 pyspark shell 时，然后键入以下两行：
spark = SparkSession.builder.appName("preprocessing").config("spark-master", "local").getOrCreate()
df = spark.read.format("csv").option("header","true").option("inferSchema", "true").option("delimiter",",").load("src/census-income.data")
发生错误：
2018-10-02 19:55:24 ERROR PoolWatchThread:118 - Error in trying to obtain a connection. Retrying in 7000ms
java.sql.SQLException: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.setReadOnly(Unknown Source)
at com.jolbox.bonecp.ConnectionHandle.setReadOnly(ConnectionHandle.java:1324)
at com.jolbox.bonecp.ConnectionHandle.<init>(ConnectionHandle.java:262)
at com.jolbox.bonecp.PoolWatchThread.fillConnections(PoolWatchThread.java:115)
at com.jolbox.bonecp.PoolWatchThread.run(PoolWatchThread.java:82)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: ERROR 25505: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.impl.sql.conn.GenericAuthorizer.setReadOnlyConnection(Unknown Source)
at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.setReadOnly(Unknown Source)
... 8 more
- 火花版本：2.3.2
- 蟒蛇版本：3.7.0
您可以尝试从当前目录 (SPARK_HOME( 中删除文件metastore_db/dbex.lck吗？
来源： https://github.com/bpn1/ingestion/wiki/Troubleshooting
Spark 正在尝试从 HDFS 加载。显然你没有安装Hadoop，Spark无法连接到HDFS。 如果要从加载加载，则必须显式指定：
file:///src/census-income.data