Thanks for your response. You are right, I have a test machine that I use for testing SQL conversion between MySQL and PostgreSQL. I only run the upgrade scripts there. It would be nice for you to provide the upgrade scripts with the correct table definitions.
I would just like to point out that the upgrade sql statements for seahub has new table definitions even in 6.3.
I have been trying to maintain the PostgreSQL compatibility that no longer has upgrade scripts. So I am currently running 6.2.5 with PostgreSQL due to the fact I was a very early adopter of Seafile (back in version 1 days) when PostgreSQL support was included although unofficial. They are on github https://github.com/caniwi/seafile-postgres-updates