class ActiveRecord::ConnectionAdapters::MySQL::ExplainPrettyPrinter

:nodoc:

def build_cells(items, widths) 

def build_cells(items, widths)
  cells = []
  items.each_with_index do |item, i|
    item = "NULL" if item.nil?
    justifier = item.is_a?(Numeric) ? "rjust" : "ljust"
    cells << item.to_s.public_send(justifier, widths[i])
  end
  "| " + cells.join(" | ") + " |"
end

def build_footer(nrows, elapsed) 

def build_footer(nrows, elapsed)
  rows_label = nrows == 1 ? "row" : "rows"
  "#{nrows} #{rows_label} in set (%.2f sec)" % elapsed
end

def build_separator(widths) 

def build_separator(widths)
  padding = 1
  "+" + widths.map { |w| "-" * (w + (padding * 2)) }.join("+") + "+"
end

def compute_column_widths(result) 

def compute_column_widths(result)
  [].tap do |widths|
    result.columns.each_with_index do |column, i|
      cells_in_column = [column] + result.rows.map { |r| r[i].nil? ? "NULL" : r[i].to_s }
      widths << cells_in_column.map(&:length).max
    end
  end
end

def pp(result, elapsed)

This is an exercise in Ruby hyperrealism :).

2 rows in set (0.00 sec)
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
| 1 | SIMPLE | posts | ALL | NULL | NULL | NULL | NULL | 1 | Using where |
| 1 | SIMPLE | users | const | PRIMARY | PRIMARY | 4 | const | 1 | |
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+

MySQL shell:
Pretty prints the result of an EXPLAIN in a way that resembles the output of the
:nodoc: 
def pp(result, elapsed)
  widths    = compute_column_widths(result)
  separator = build_separator(widths)
  pp = []
  pp << separator
  pp << build_cells(result.columns, widths)
  pp << separator
  result.rows.each do |row|
    pp << build_cells(row, widths)
  end
  pp << separator
  pp << build_footer(result.rows.length, elapsed)
  pp.join("\n") + "\n"
end