indexes

# 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