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
).
Java Version
The JDBC driver is compatible with Java 8, 9, 10 and 11. The JDBC driver included in the Denodo 7.0 update 20190312 or earlier requires Java 8.
Backward Compatibility
Virtual DataPort is backward compatible with its JDBC driver and other clients, within the same major version. That is, to connect to a Virtual DataPort that runs with a certain update, use the JDBC driver of that update or an older update. Examples:
To connect to a Denodo server version 7.0 update 20181011, use the JDBC driver included in the same update, in 7.0 20180926, in 7.0 20180611 or in 7.0 GA.
Do not use the JDBC driver of 7.0 20181011 to connect to a Virtual DataPort 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 7.0 GA or any 7.0 update returns an error when trying to connect to Denodo 8.0, or to Denodo 6.0 or earlier.
Driver Class Name
The class name of this driver is the following:
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
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: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 thejava.sql.Statement
class. When a query is cancelled, the Virtual DataPort Server will cancel all current accesses to data sources and cache. After invoking thecancel
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 theResultSet
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, theResultSet
objects are closed when the current transaction is committed (i.e.CLOSE_CURSORS_AT_COMMIT
).Support for JDBC escape syntax for timestamp, date, and time literals (see Queries with Datetime Literals).