About Database Lookup

Isight has the capability, prior to executing an application component, to examine all past executions (or only those within the current job) of the application component to find out if the application component has been run with this exact set of input values. If so, the assumption is that the output values will be identical and can be restored. Isight can restore these values rather than executing the application component. For long-running application components, such as simulation codes, this can reduce execution time because the results are already in the database.

By default, database lookup is disabled to maintain backward compatibility with previous versions and for cases where database lookup is not feasible to use (e.g., the component is designed to produce an external effect, such as generating an e-mail).

Control of Database Lookup at Model/Component Levels

Database lookup can be controlled at the model level (see Setting the Execution Options) and at the component level (see Configuring the Database Lookup in the Isight Component Guide). If the model enables database lookup, all application components in the model are enabled for database lookup, except for components whose metamodels do not allow database lookup (e.g., the Mail component). Similarly, if the model does not allow database lookup, all application components in the model are disabled for database lookup.

Parameter Handling During Database Lookup

Isight handles file parameters similarly to parameter values with respect to database lookup. The checksum of a file parameter’s contents are used as the logic value for comparisons. Regular parameters must be saved to the database for database lookup to function; however, if file parameters are not saved to the database, they are simply ignored during database lookup.

If you saved all file parameters to the database but you know they all hold static data that are not driven by the model, these data are not needed for database lookup. In this case you can tell Isight to ignore all file parameters while performing database lookup, which may save execution time and computational cost. Similarly, if you know that a particular file parameter holds static data, you can choose to not save this file parameter to the database so that it will be ignored during database lookups.

Use with the SIMULIA Execution Engine

For a SIMULIA Execution Engine, database lookup bypasses the distribution of the component to the SIMULIA Execution Engine station and reduces the execution in the SIMULIA Execution Engine simulation process flow, saving the additional dispatch time in a SIMULIA Execution Engine environment.