If you want to know the actual compatibility list first, instead of marketing speak, check out this link: <a href="https://cloud.google.com/spanner/docs/reference/postgresql/overview" rel="nofollow">https://cloud.google.com/spanner/docs/reference/postgresql/o...</a><p>Spoiler: no stored procedures or triggers, amongst other stuff.
It's disappointing that each database can only talk <i>one</i> SQL dialect.<p>That means every application that accessed the database will have to use the same, and any migration will be a <i>lot</i> of work.