clone_table_with_sequel.rb

def clone_table(src_db, dest_db, table, key_field = nil, filter = nil)
  # filter the rows to be cloned
  src_ds = src_db[table]
  filter.each_pair{|k, v| src_ds = src_ds.filter(k => v)} unless filter.nil?

  # truncate if no key_field
  unless key_field
    puts "truncating #{table}..."
    dest_db[table].delete 
  end

  # Set up progress bar
  records = src_ds.count
  puts "cloning #{records} records for #{table.to_s}"
  pbar = ProgressBar.new(table.to_s, records)

  # Copy the data
  src_ds.each do |values|
     dest_db[table].filter(key_field => values[key_field]).delete if key_field
     dest_db[table].insert(values)
     pbar.inc
  end
  pbar.finish
  puts "Destination now has #{dest_db[table].count} records in #{table}"
  src_ds
end