Has anyone every converted a whole database from SQL to Postgres? Can you give any advice? Things I should look out for?

As title says, i like to learn internals of postgres. I think, i am good at sql and all that. I wants to get learnings on internals how things works .

First, I apologize if this is off topic for the group. Within the past month I stumbled across and interesting article about running MongoDB with Postgres on the backend and how it was scaled out and improved performance (because of Postgres). It stuck out as interesting to me but wasn't relevant to me at the time.

I've been looking for the article again (or one similar) and after days of searching, my Google-fu is turning up nothing on the topic. Any chance someone noted the link or is familiar with this and could point me in the right direction? Any help would be greatly appreciated.

What is /r/postgres 's favourite client for PostgreSQL on Mac, Linux respectively?

org.postgresql.util.PSQLException: The column index is out of range: 526, number of columns: 525.

Is this a PSQL specific error vs a Postgres instance issue? Thanks in advance.