Display changed row counts using ActiveRecord

display_changed_row_counts.rb

def row_counts
  Hash[*ApplicationRecord.connection.execute(%{
    ANALYZE;
    SELECT
      pgClass.relname   AS tableName,
      pgClass.reltuples AS rowCount
    FROM
      pg_class pgClass
    INNER JOIN
      pg_namespace pgNamespace ON (pgNamespace.oid = pgClass.relnamespace)
    WHERE
      pgNamespace.nspname NOT IN ('pg_catalog', 'information_schema') AND
      pgClass.relkind='r'
  }).values.flatten]
end

def display_changed_row_counts
  original_counts = row_counts
  yield
  new_counts = row_counts
  new_counts.keys.sort.each do |table_name|
    original_count = original_counts[table_name].to_i
    new_count = new_counts[table_name].to_i
    unless new_count == original_count
      puts "#{table_name}: #{original_count} -> #{new_count} (#{'%+d' % (new_count - original_count)})"
    end
  end
end