We have a system that we’ve installed at 4 locations using Ignition, and all those systems are running fine. We put together a demo system, and the demo system has very poor performance related to the Tags historian. The production systems connect with ~50 Modbus devices, utilizing ~30 tags each and on those systems we see update rates of 1 second intervals for the devices we’re connected to. On the demo system, we are seeing updates of 10-20 seconds, and it’s only connected to 3 devices. In order to save weight and cost, the demo system is running Windows 7 and SQL Express instead of Server 2008 and MS SQL Standard. The demo system uses a Intel Core i7-3612QE (2.1Ghz Quad core) with 16Gb of memory, so I don’t think the performance is related to the CPU. Is SQL Express hamstrung and not capable of running the tags historian? Is the issue Windows 7? Has anybody else used SQL Express with the tags historian with success? I’m running Ignition 7.8.2 and Java 1.8.77.
My understanding is that SQL Express is limited to a single CPU and 1Gb RAM, no matter what your machine has. Not sure if there are other limitations under the hood (simpler query optimizer, for example) that would affect performance.
Finally had a chance to look at this again after more experience. Turns out the poor performance was simply the Default Historical scan class being set to 10 second intervals and not 1 second intervals. The data I was watching a the time had peaks that were shorter than 10 seconds and weren’t recorded. The issue had nothing to do with SQL Express.