Bloomy Blog EFT On-The-Fly Database Reporting

October 31, 2022New feature of Bloomy's EFT Module for TestStand improves data recovery in the event of a crashBloomy recently added a new feature to the database reporting function of the EFT Module for TestStand. This new feature allows real time, also known as on-the-fly (OTF), data logging to a database. Now you have two options of how you can log your test data to a database: 1) traditional batch data logging, or 2) OTF data logging.Before we take a look at which data logging option is best for your use case, let's first get a better understanding of how each of these data logging features operate.Understanding the two database reporting optionsIn the traditional batch data logging mode, the test result data is pushed to the database when all of the testing is completed. That is, in TestStand, when the test sequence has completed executing all of its test steps, all of the test data (aka a "batch" of data) is pushed to the database at one time. Depending on the data captured during the entire test sequence, this can be a significant amount of data. We'll talk more about this in a minute.OTF datalogging pushes smaller amounts of data to the database much more frequently, or "on-the-fly". For example, during the execution of a TestStand test sequence, after every test step completes execution, the test data from that test step is pushed to the database. In this mode, smaller sets of test data are pushed to the database many times during a test cycle.When to use batch vs. OTF database loggingOkay, now that we have a fundamental understanding of each database reporting feature, let's compare the pros and cons of each approach. BatchOn-The-FlyProsMaximizes test sequence execution speedMinimizes memory usageMinimizes potential data loss in the event of an issue preventing completion of the test sequenceMost reliable and robust, can usually recover any data logged prior to any catastrophic failureConsCan consume large amounts of memoryCould lose data before it is pushed to database in the event of a catastrophic failure during testing (i.e., PC crash, etc.)Will add some overhead to test execution timeRecommendationBest for high-speed testing of short-duration tests with small data sets logged locallyBest for long-term or mission-critical testing, as well as networked dataloggingRecommended in all cases where an additional latency during testing isn't prohibitiveTaking a closer look at these pros and cons...While the batch datalogging does offer the advantage of optimizing test execution, this does come with a caveat: If your test is capturing large amounts of data and/or running for extended periods of time, then this data will start to consume memory (which is unbounded). This can affect the operation (speed) of the PC, which can slow down test execution over time. On the con side for batch datalogging, again, if your tests are relatively long, not only are you consuming more memory, but there is the potential to lose all of that data if a catastrophic event were to occur during test, such as a PC crash.OTF mitigates the cons of the batch datalogging by writing smaller amounts of data to the database at more frequent intervals. This minimizes memory usage and helps to mitigate the potential loss of data due to a catastrophic event. The con of OTF is that there will be some overhead added to the test execution time as the data is pushed to the database during the test cycle (at the end of every test step). Also, be aware that if the data rate capture is faster than the configured OTF processing strategy, there may be a stack-up of temporary data files, that should resolve itself in most practical situations.Okay, so we are finally to the point where we can make some decisions on when to use either of these datalogging features. As pointed out in the pros and cons, for any testing that is executed over a long period of time, such as hours long environmental stress screening (ESS) testing, it is best to use the OTF datalogging option. For short duration test cycles where test optimization is critical as is often the case with functional test, utilizing the batch datalogging feature is probably the wise choice.In summary, either feature will work for you. The key parameters you need to keep in mind are: 1) Is test time optimization important?, 2) How much test data am I collecting?, and 3) Is the test cycle long where the potential loss of data, and increased memory usage, is important to mitigate? Based on what is most important to your test requirements, and referring to the pros and cons table, the obvious choice as to which datalogging feature you choose should become apparent.Related linksDownload the EFT Module for TestStandLesser-Known Features of The EFT Module for TestStandCategory: Electronics Test