Goal
This document describes how to connect to Jethro from the Denodo Platform.
Jethro is middleware software that resides between BI clients and underlying Hadoop or AWS clusters. From Denodo, we can retrieve data from Jethro by creating a JDBC data source using Jethro’s JDBC Driver.
Connecting to Jethro from Denodo
- Download Jethro’s JDBC driver from https://jethro.io/driver-downloads and import the JDBC driver using the File > Extensions management option as described in the Importing a JDBC Driver section of the Virtual DataPort Administration Guide.
- From the Denodo Web Design Studio, create a new JDBC data source by choosing File > New > Data Source. A window will appear to select a data source type, search JDBC and choose Generic Database (JDBC). This will open a wizard to create a connection to a data source with a JDBC driver.
- To establish a connection, fill the following fields:
- Name: ds_jethro
- Database URL: jdbc:JethroData://<server>:<port>/<schema>, for example jdbc:JethroData://192.168.x.x:9111/demo
- Authentication: Use Login and Password
- User: Username for jethro (by default jethro)
- Password: Password for jethro (by default jethro)
- Switch to the Advanced tab:
- Driver Class Path: Under Other JDBC Drivers choose the Jethro one.
- Driver Class: com.jethrodata.JethroDriver
- Click Test Connection. If the test is successful, click Save.
3. Source Configuration:
Jethro does not support Prepared statements. Therefore open the Virtual DataPort Administration Tool and set Allow Literal as Parameter to No in the Source Configuration tab of the data source.
In addition to that implicit joins are not supported, the join condition must be explicit to make it work. To configure this set Supports Explicit CROSS JOIN and Supports JOIN ON condition to Yes.
Change the value of the following properties in the Source Configuration of the data source and save the view.
Source Configuration Property |
Value |
Allow Literal as Parameter |
No |
Supports Explicit CROSS JOIN |
Yes |
Supports JOIN ON condition |
Yes |
Note:
In some situations, data retrieval may be slow when trying to access large data sets. In order to improve the performance, try to increase the value of the Fetch size parameter in the Data Source Configuration based on your requirements.
This property will give a hint to the JDBC driver about the number of rows that should be fetched from the database when more rows are needed. By default, the value of this property is 1000 rows.
Creating Base Views
Once these changes are done, click on the Create base view tab to introspect source metadata available through the Data Source. Select the views you want to create a base view over and then, click the Create selected.
Query the base view to start retrieving data from Jethro.
References
Data Source Configuration Properties
The information provided in the Denodo Knowledge Base is intended to assist our users in advanced uses of Denodo. Please note that the results from the application of processes and configurations detailed in these documents may vary depending on your specific environment. Use them at your own discretion.
For an official guide of supported features, please refer to the User Manuals. For questions on critical systems or complex environments we recommend you to contact your Denodo Customer Success Manager.