The last straw was when Oracle bought MySQL, and it was forked to MariaSQL. Postgres went from the nerdy awkward kid to the nerdy cool kid, while MySQL started drinking, getting split personalities, and living off his past fame.
I think even Sun buying MySQL already hurt MySQL and helped PostgreSQL.
Back in 2006, the startup I was with moved from PostgreSQL to MySQL because the support we were able to find was both expensive (300 USD/hr) and not satisfactory. Back then MySQL AB (this was before Sun) gave us a 10K two year deal on three servers and they had excellent response times and knowledgeable support.
For PostgreSQL the year 2010 when Salesforce bought Heroku (big plus) and Oracle bought MySQL (big minus for MySQL so indirect big plus to PostgreSQL) was the breakthrough, I would say.
That MySQL didn't get CTE and window functions until 2018 is a sad joke.
It was my mistake, I misremembered MariaDB, but can't edit my comment now. In my defense, I've barely thought of it since 2009, when it was forked.
On the other hand, I've worked with MySQL a few times in the same period, mostly because Oracle, whatever its failings, has kept MySQL alive. Not thriving, but alive. I'm so glad they didn't buy PostgreSQL.
