Mathematica AppData folder is taking up too much space

Question

I recently made a small app that I had issues with. I'm pretty sure it ended up being because of all the curated data to load. My problem now is that under the Windows 8.1 folder Users/Username/AppData/Roaming/Mathematica/Paclets/Temporary, there is 10GB of "GraphData" files. I have a small SSD and I need to get rid of this stuff. Now I'm assuming I can probably delete it, but I thought I'd ask if there's a proper way to delete this stuff (like a certain command or something). And finally, is there a way of preventing Mathematica from downloading so much data onto my computer, or at least deleting it once I'm done with it? That one day I loaded up my app, I lost 10 GB over the course of a couple hours.

The real question here is: why does Mathematica generate a rather large folder of data from the use of one notebook, and not clear it somehow afterwards? Is there a way of configuring how much temporary curated data is stored on your computer? Is there a way of clearing it without actually deleting the contents of the folder?

Answer 1

Late to the party: I found this question today while testing out how to apply time constraints to functions accessing curated data (How to set the timeout value for *Data functions).

In order to test a function accessing curated data, I had to clear the cached data on my computer, so I could reproduce the conditions of a first access and the accompanying long loading times. I was trying to figure out whether there is a nice programmatic way to flush local data for a particular repository. I couldn't find any, but I found this question.

In my case, the data was associated with WeatherData results, and it was residing in folders name WeatherData*, and CityData*. It had been generated from evaluation of the following expression:

WeatherData["Chicago", "Temperature", {1950, 1}]

Eventually, I just decided to test out what would happen if I simply deleted the data while Mathematica was running. For what it's worth, I'm on MMA v. 10.1 on Win7-64bit, also on an SSD.

The results were very benign:

• the WeatherData folders could be deleted just fine, but the CityData* folder could not, indicating to me that Mathematica had those files open at the time.
• I then Quit[] the kernel from the front end; I could then delete the remaining CityData* folders.
• Restarting the kernel and evaluating the same expression re-downloaded the data and re-generated the indices with no complaints.

Of course this is little more than a commentary to the OP's main question regarding transparent management of downloaded data. That part is still wide open, but I don't think that mere users can answer that one without insight from WRI...