What's the implication of deleting /usr/local/var?

Question

On MacOS, what's the implication of deleting /usr/local/var (when it contains the following 3 folders - homebrew, run and mysql)?

Note, you can assume I don't care about anything in the mysql folder because I want to delete it. (but I want to know what would happen to the other two folders (I can imagine the homebrew folder contain homebrew related stuff but I don't know what the run folder does at all).

Also, I used ls to list the content of /usr/local/var folder before I delete it so that means I may have missed some content that can be displayed by ls -la, so if there are any other files that I may have missed, can you tell me as well?

Debugging info:

$ brew --version
Homebrew 1.6.9
Homebrew/homebrew-core (git revision 7dac; last commit 2018-06-20)

System Version: macOS 10.13.5 (17F77)

Kernel Version: Darwin 17.6.0

I didn't do any backup and didn't use Time Machine.

Answer 1

What are the implications?

Since /usr/local one of the explict directories that SIP (System Integrity Protection) allows applications to write to, you will only harm applications that you install.

Will you crash the overall system?

No.

Will you make your system "unusable" based on what you've installed and configured?

More than likely.