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Today I randomly had an issue where none of my Vagrant machines were booting up. Going into the Virtualbox GUI I tried to manually start the VM and I get the ominous, but somewhere helpful error code VERR_SUPLIB_OWNER_NOT_ROOT. Thinking back to stupid things I might have done today- I realized that I had done:

I did this because there was an application installed as administrator that constantly popped up the “This was downloaded from the internet…” popup and it was never going away. So I went in and chowned /Applications/ to root:admin and… no luck. Uninstalled and reinstalled VirtualBox… no luck. Finally I happened upon this old bug ticket from years ago ( that confirmed my suspicions. I simply had to run the following to get everything working again:

After that, everything works like a charm and I realize that I probably shouldn’t have done the chown -R in the first place.

Use Subqueries to Speed Up Count Distinct

This is an awesome post by the thoughtful folks at on how you can think about optimizing your queries (in this case COUNT DISTINCT) for maximum speed.

Read it here