Query Inside Loop (ARCH6064)

Key ruby.orm.query-inside-loop · Severity warning · Category orm

Any DB query inside a loop body (broader than relation N+1: includes ad-hoc find, aggregates, repository calls) produces one round-trip per iteration.

Incorrect

ids.each do |id|
  user = User.find(id)  # a separate query per iteration
  process(user)
end

Correct

users = User.where(id: ids)  # all in one query
users.each { |user| process(user) }

Fix

Hoist queries out of the loop so the needed records are fetched in a single query beforehand.