DB loading E+ data is Slooooow

johntaylor · Posts: 52

Have you put effort into the code efficiency for loading the data back from E+? Right now it is unbearable. It often takes 3 times as long to load the data than to simulate it. This is crazy slow.

It is hard to believe that it could take 3X longer to load the data from the simulation, than it took to run the simulation and generate the output files!?! 45 minutes to load data to graph it on a 2 core, 3 GB RAM machine? What is going on? Even it generated gigabytes of data, what is keeping you from displaying it in less than 1 minute?

Laurent_Support · Posts: 292 Location: Vincennes

Hello,

Could you tell us what is the eso file size created by the simulation (in EnergyPlus Folder)?

Hourly simulation on a year for every data could easily generate more than 100Mo outputs. This is generally the reason why loading is so long.

The best strategy I know and use is to limit simulation outputs to your needs. Especially annual or months simulation. Check (or uncheck) every boxes you need in the outputs tab to limit data production.
Another way is to ask for monthly or daily data instead of hourly.

I hope this will help you!
Laurent

johntaylor · Posts: 52

Laurent,

The load time is about 2-3 times as long as the simulation time regardless of the time to simulate. So a 3 minute simulation is 7-9 minutes in load time. A 20 minute simulation takes about 40 minutes to load.

It is a really important problem. I hope you address it soon. I was concerned about E+ simulation speed, but actually it very reasonable compared to just the loading time into DB.

Clearly DB could do this much more efficiently. If EnergyPlus can simulate AND write out all of the files in a third the time DB can just display them, then you know it is a problem.

Right now a Days worth of simulation take 3 days instead. Which is too expensive for me to afford.

Andy Tindale · Posts: 1196 Location: Stroud

John, you should generally avoid requesting hourly or sub-hourly results for annual simulations - this is almost certainly the cause of the slow data reading. We will look at improving reading speed in the future, but it is important to be clear that even with optimal data reading, given that DB stores results in memory (not database file), very large data sets will slow the software down and generally aren't practical.

Look at hourly results for summer, winter and swing season weeks then when you are happy that the model is accurately representing your building switch off hourly results and work with annual data.

Andy

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