Driver resources

The database driver resources are configuration parameters you can set to modify the behavior of the LN MSQL database driver. These parameters are set in the resource file (db_resource). One resource file is available for all database drivers that run in an LN environment. Resources for all database driver offerings can be set there. The database driver reads the parameters set in the resource file when it is first invoked and uses these settings to configure itself.

The resource file can contain multiple entries with one entry per line. Each entry is used to set a single resource parameter, with the resource name followed by a colon and then the value to which the resource must be set.

The following is an example of the contents of a resource file containing two entries: 

msql_opt_rows:10 
msql_lock_timeout:60

When modifying the behavior of the database driver, you must frequently modify the behavior of the LN application virtual machine to take advantage of the characteristics of the database driver. Therefore, two types of database driver resources are available:

  • Resources used to modify the behavior of the database driver.
  • Resources used to modify the behavior of the database driver’s client (for example the application virtual machine).

Driver resources used to modify database driver behavior are called resources for the server. Driver resources used to modify behavior in the application virtual machine are called resources for the client.

The db_resource file is located in the folder where the LN software environment is installed.

  • On Windows: %BSE%\lib\defaults

$BSE and %BSE% refer to the folder in which the LN software environment is installed.

When the database driver and the application virtual machine run on the same machine, one db_resource file contains all required resource parameters.

When the database driver and the application virtual machine run on separate machines, a db_resource file is required on the server that runs the:

  • Database driver containing the server resources.
  • Application virtual machine containing the client resources.

Besides the default resource file db_resource, you can set up an alternative resource file to override resource values for specific users or groups of users. The alternative resource file is specified with the environment variables USR_DBS_RES and USR_DBC_RES. You can use the USR_DBS_RES variable to specify the path to a file that contains an alternative resource file for the server. You must set this variable on the machine that runs the database driver. Specify the path to a file that contains an alternative resource file for the client in the USR_DBC_RES variable. Set this variable on the machine that runs the application virtual machine. Any driver resource set in the alternative resource file overrides the setting of the same driver resource in db_resource.