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Driver Overview

The drivers tab allows you to manage the jdbc jar file that will be provided to the application or used by the proxy.

Fields

Fields can be found in drivers options

AWS Cluster Tracking

In order to account for various configurations that may be desired, if load balancing is enabled, and cluster tracking is enabled, the reader and writer URL patterns will be used to generate the actual JDBC URL's to represent the various nodes of the cluster. The reader and write URL's can contain the following variables for substitution, which should be used based on the information extracted from the AWS configuration:

Variables can be found in Reader and Writer variables

If the writer URL includes the string ":replication:" AND there is only one node in the cluster, then the value for the writer will be duplicated twice in the reader list. This is to avoid a degenerate case for the MySQL driver where a "replication" url requires two hosts to be defined, or it will fail to connect to any host. By duplicating the host twice, it passes the check, and will work as expected.

Advanced

When a vendor driver is used by the Heimdall driver, we will first attempt to load the driver remotely, i.e. by downloading the driver from the central manager. This provides a single source for the drivers, simplifying the management of the drivers. If this fails, it will attempt to use the local class loader in order to find the driver. In an OSGI Java environment, it may be necessary to package the database driver with the Heimdall driver as a dependency in order for all behaviors to work as expected if the remote load feature does not work.

Proxy vs. JDBC Driver Behavior

When using Heimdall in proxy mode, it is highly recommended that the drivers provided in the Heimdall install package be used. This is as a result of the tight integration work that is done with Heimdall to operate with these drivers, and may be broken between release builds of the vendor driver. In JDBC mode, this requirement can be ignored, and the application recommended version of the drivers should be used.