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.

Denodo provides a JDBC type 4 driver that implements the main characteristics of the JDBC 4.1 API (Java Database Connectivity).

You can get the Denodo JDBC driver from:

• The Denodo Community (https://community.denodo.com/drivers/jdbc/). Download the version of the update installed in the Denodo server. To find out the version of the Denodo server you are connecting to, log in to that server with the administration tool, click the menu File > About… and look for VDP server (below installed updates).

• Or from the installation (<DENODO_HOME>/tools/client-drivers/jdbc/vdp-jdbcdriver-core/denodo-vdp-jdbcdriver.jar).

The JDBC driver is compatible with Java 8, 9, 10 and 11.

The Virtual DataPort server is backward compatible with the JDBC driver and other clients, within the same major version, but not the other way around. That is, the Denodo JDBC driver of an update can be used to connect to the Virtual DataPort server with the same update or a newer update. For example:

• To connect to a Denodo server version 7.0 update 20181011, you can use the JDBC driver included in the same update or the driver included in 7.0 20180926, 7.0 20180611 or 7.0 GA.

• Do not use the JDBC driver included in 7.0 20181011 to connect to a Denodo server version 7.0 update 20180926 because the driver is more recent than the server. This is an unsupported configuration; some operations may fail.

• The JDBC driver of Denodo 8.0 GA or any 8.0 update will return an error when trying to connect to Denodo 7.0 or earlier.

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

The syntax of the database URL is

jdbc:vdb://<hostName>:<port>/<databaseName>[?<paramName>=<paramValue> [&<paramName>=<paramValue>]* ]

The name of the database is mandatory.

For example:

jdbc:vdb://localhost:9999/admin?queryTimeout=100000&chunkTimeout=1000&userAgent=myApplication&autoCommit=true

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: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).

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).