did google even use mysql? certainly if they did they never talked about it publicly in the early 02000s, and of course facebook didn't even exist then
lj, though, they used the fuck out of mysql
/. originally didn't use a database; i (an ordinary user) accidentally posted an article by trying to post a comment on an article that didn't exist yet; i guess they got appended to the same file. but when it did switch to a database (i don't know, about the time google was founded?) it was of course mysql