The Value Cache is, amongst other things, a temporary storage location for data belonging to interviews that are not yet complete. These might be interviews that are in progress, or that have either been stopped or have timed out. If a project has its AutoUpdateDataModel property set to 1 (the default), data is written to the case data database for each submitted page. When the AutoUpdateDataModel property set to 2, data is written to the case data database as soon as respondents give their answers, so in this case the cached files are mainly used for rolling back or restarting interviews.

When AutoUpdateDataModel is set to 0, data is written to the case data database by the Transfer Service. This scans the Value Cache for files belonging to completed interviews and transfers the data from those files into the database. Files for interviews that have been stopped or that have timed out are not automatically transferred and are normally deleted after 48 hours' inactivity. If a project manager decides that they wants to include data for incomplete interviews in the case data, you must flag these files so that the Transfer Service can read them.

The Transfer Service is also useful if there are problems writing data or communicating with the database server when AutoUpdateDataModel is set to 1. In this case, the data remains in the value cache and is treated exactly the same as if AutoUpdateDataModel had been set to 0. That is, if the interview completes, the data is transferred automatically the next time the Transfer Service runs. If the interview times out or is stopped, the data remains in the cache and you can decide whether or not to flag it for transfer.

Use FlagInterviewsForTransfer.mrs only when absolutely necessary. It might lead to samples becoming stuck in the ACTIVE queue. The issue can occur when the FlagInterviewsForTransfer.mrs script changes a cache file. The session engine identifies the cache file as changed from an outside process and reports the sample as a failover to the other engines (processing ceases at this point).

The next time the Transfer Service runs, it reads the files for stopped and timed out interviews as well as those for newly completed interviews. If a file cannot be transferred it will be treated the same as files for completed interviews.

To find out more about the FlagInterviewsForTransfer.mrs script, open it in UNICOM Intelligence Professional or using a text editor such as Notepad and read the comments.

To find out more about mrscriptCL, see mrScript Command Line Runner.