I remember going to a general community-run tech conference in Vienna in 2002 and there was a talk on PostgreSQL which I'd never heard of at that point (had been using MySQL and Oracle). The person giving the talk was a nerd and quite enthusiastic, and quite sad that PostgreSQL wasn't more popular. Come to think of it, I guess that person is happy now :)
So I would say it was already "cool" at that point (albeit not in wide use, at least in my circles).
We weren't too happy with Oracle (pricing), and we'd only moved to that after being unhappy with MySQL in 2000 (no transactions!). I think PostgreSQL would have been a good choice for us, and I did give it a try, but migrating all the data out of Oracle just didn't really seem possible (Oracle didn't provide great export tools as you can imagine, and a "SELECT col1 || "," || col2 .." type of thing to produce a CSV would have taken hours per table and we had a few dozen tables, so would have either resulted in days of downtime, or some funky logic with a lookup table to say which database a user was in and moving them over one-by-one, but then what about FKs? what about a "messages" table where one user sends a message to another? etc. So on Oracle we stayed until the end of the product around 2012.
So I would say it was already "cool" at that point (albeit not in wide use, at least in my circles).
We weren't too happy with Oracle (pricing), and we'd only moved to that after being unhappy with MySQL in 2000 (no transactions!). I think PostgreSQL would have been a good choice for us, and I did give it a try, but migrating all the data out of Oracle just didn't really seem possible (Oracle didn't provide great export tools as you can imagine, and a "SELECT col1 || "," || col2 .." type of thing to produce a CSV would have taken hours per table and we had a few dozen tables, so would have either resulted in days of downtime, or some funky logic with a lookup table to say which database a user was in and moving them over one-by-one, but then what about FKs? what about a "messages" table where one user sends a message to another? etc. So on Oracle we stayed until the end of the product around 2012.