Method: ActiveRecord::ConnectionAdapters::MySQL::SchemaStatements#indexes

Defined in:
activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb

#indexes(table_name) ⇒ Object

Returns an array of indexes for the given table.



8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
 
# File 'activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb', line 8

def indexes(table_name)
  indexes = []
  current_index = nil
  internal_exec_query("SHOW KEYS FROM #{quote_table_name(table_name)}", "SCHEMA").each do |row|
    if current_index != row["Key_name"]
      next if row["Key_name"] == "PRIMARY" # skip the primary key
      current_index = row["Key_name"]

      mysql_index_type = row["Index_type"].downcase.to_sym
      case mysql_index_type
      when :fulltext, :spatial
        index_type = mysql_index_type
      when :btree, :hash
        index_using = mysql_index_type
      end

      indexes << [
        row["Table"],
        row["Key_name"],
        row["Non_unique"].to_i == 0,
        [],
        lengths: {},
        orders: {},
        type: index_type,
        using: index_using,
        comment: row["Index_comment"].presence
      ]
    end

    if expression = row["Expression"]
      expression = expression.gsub("\\'", "'")
      expression = +"(#{expression})" unless expression.start_with?("(")
      indexes.last[-2] << expression
      indexes.last[-1][:expressions] ||= {}
      indexes.last[-1][:expressions][expression] = expression
      indexes.last[-1][:orders][expression] = :desc if row["Collation"] == "D"
    else
      indexes.last[-2] << row["Column_name"]
      indexes.last[-1][:lengths][row["Column_name"]] = row["Sub_part"].to_i if row["Sub_part"]
      indexes.last[-1][:orders][row["Column_name"]] = :desc if row["Collation"] == "D"
    end
  end

  indexes.map do |index|
    options = index.pop

    if expressions = options.delete(:expressions)
      orders = options.delete(:orders)
      lengths = options.delete(:lengths)

      columns = index[-1].to_h { |name|
        [ name.to_sym, expressions[name] || +quote_column_name(name) ]
      }

      index[-1] = add_options_for_index_columns(
        columns, order: orders, length: lengths
      ).values.join(", ")
    end

    IndexDefinition.new(*index, **options)
  end
rescue StatementInvalid => e
  if e.message.match?(/Table '.+' doesn't exist/)
    []
  else
    raise
  end
end