visit_IndexDefinition

# File activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb, line 42
          def visit_IndexDefinition(o, create = false)
            index_type = o.type&.to_s&.upcase || o.unique && "UNIQUE"

            sql = create ? ["CREATE"] : []
            sql << index_type if index_type
            sql << "INDEX"
            sql << quote_column_name(o.name)
            sql << "USING #{o.using}" if o.using
            sql << "ON #{quote_table_name(o.table)}" if create
            sql << "(#{quoted_columns(o)})"

            add_sql_comment!(sql.join(" "), o.comment)
          end