[buro9]

gresrun works at YouTube, if by reference you mean citation then his comment is it.

[jjnoakes]

wikibob was probably looking more for public documentation about the why and how rather than confirmation that the statement is true.

[wikibob]

Yep, I love watching conference talks or reading Twitter threads, papers, etc about these kind of migrations.

[owaislone]

Probably because Youtube was using MySQL before being acquired and switched to a better, probably fully managed DB that was much easier (free?) to maintain and scale.