That's fine for tiny amounts of data, but it's also how you end up with (for example) Ruby taking four minutes to do what a carefully-crafted SQL query can do in four seconds (yes, this stuff happens a lot in the wild)
Yah, somebody handed me a ruby script that looped over a query and was causing a whole bunch of other processes to fail because the result wasn't available in a timely way. My boss was impressed by my having reduced the run time from 22 minutes to 5 by pushing that join into the database.
