Another Railsism I just learned about is the .find_each method which can be used to replace the .each method on large queries that will return more than 1,000 records.
Unlike my previous posts .find_each is not part of active support, and looks like it is part of active record.
Without .find_each you could run into a memory issue when just using .each:
Topic.where(archetype: "private_message").each do |pm|
# do something
end
if there were thousands of records. But .find_each will by default use batches of 1000:
Topic.where(archetype: "private_message").find_each do |pm|
# do something
end