Access Through JDBC

JDBC (Java Database Connectivity) is a Java API that allows executing statements on a relational database regardless of the Database Management System used.

Virtual DataPort provides a driver that implements the main characteristics of the JDBC 4.1 API (Java Database Connectivity). These are some of the features of the JDBC specification supported by the Virtual DataPort JDBC driver:

  • The data types supported are defined in the VQL Guide (includes support for all basic types and for fields of the type array and register).
  • Execution of statements to query, insert, update and delete data. In addition, to create new elements such as data sources, views, etc.
  • Support for metadata description statements and listing of server catalog elements.
  • Support for PreparedStatements.
  • Support for canceling the current statement execution by using the cancel() method of the java.sql.Statement class. When a query is cancelled, the Virtual DataPort Server will cancel all current accesses to data sources and cache. After invoking the cancel method, it is still possible for the server to return some results, if these were retrieved before the source access canceling were effective. Therefore, the query cancellation does not imply closing the ResultSet that is being used.
  • Invocation of stored procedures using the CALL statement.
  • Support for submitting batches of commands.
  • The ResultSet objects returned by Virtual DataPort are not updatable (i.e. CONCUR_READ_ONLY) and have a cursor that moves forward only (i.e. TYPE_FORWARD_ONLY). In addition, the ResultSet objects are closed when the current transaction is committed (i.e. CLOSE_CURSORS_AT_COMMIT).

The JDBC driver is at <DENODO_HOME>/tools/client-drivers/jdbc/vdp-jdbcdriver-core/denodo-vdp-jdbcdriver.jar

This directory also contains the file denodo-vdp-jdbcdriver-basic.jar is. The section When to Use the “Basic” Version of the JDBC Driver explains when you should use this jar file instead of the denodo-vdp-jdbcdriver.jar.

The class that implements the driver is com.denodo.vdp.jdbc.Driver.

The syntax of the database URL is

Syntax of the JDBC connection URL
jdbc:vdb://<hostName>:<port>/<databaseName>[?<paramName>=<paramValue> [&<paramName>=<paramValue>]* ]

The name of the database is mandatory.

For example:

JDBC connection URL sample
jdbc:vdb://localhost:9999/admin?queryTimeout=100000&chunkTimeout=1000&userAgent=myApplication

Important

The connection URL only references one port (by default, 9999). However, the driver also opens a connection to the Auxiliary port of the Denodo server (by default, 9997). Therefore, if there is a firewall between the client and the Denodo server, you need to allow connections to both ports. You can get the value of this port using the administration tool, in the menu Administration > Server Configuration, in the tab Server connectivity.

If the name of the database contains non-ASCII characters, they have to be URL-encoded. For example, if the name of the database is “テスト”, the connection URL to the database will be this:

JDBC connection URL sample with non-ASCII characters
jdbc:vdb://localhost:9999/%E3%83%86%E3%82%B9%E3%83%88?queryTimeout=900000&chunkTimeout=1000&userAgent=myApplication&autoCommit=true

The path DENODO_HOME/samples/vdp/vdp-clients contains examples of client programs accessing Virtual DataPort through JDBC (the README file of this path explains how to generate and publish the views accessed by the clients in the example).