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| layout: global |
| title: Troubleshooting |
| displayTitle: Troubleshooting |
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| --- |
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| * The JDBC driver class must be visible to the primordial class loader on the client session and on all executors. This is because Java's DriverManager class does a security check that results in it ignoring all drivers not visible to the primordial class loader when one goes to open a connection. One convenient way to do this is to modify compute_classpath.sh on all worker nodes to include your driver JARs. |
| * Some databases, such as H2, convert all names to upper case. You'll need to use upper case to refer to those names in Spark SQL. |
| * Users can specify vendor-specific JDBC connection properties in the data source options to do special treatment. For example, `spark.read.format("jdbc").option("url", oracleJdbcUrl).option("oracle.jdbc.mapDateToTimestamp", "false")`. `oracle.jdbc.mapDateToTimestamp` defaults to true, users often need to disable this flag to avoid Oracle date being resolved as timestamp. |
