visit_ChangeColumnDefinition

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb, line 88
          def visit_ChangeColumnDefinition(o)
            column = o.column
            column.sql_type = type_to_sql(column.type, **column.options)
            quoted_column_name = quote_column_name(o.name)

            change_column_sql = +"ALTER COLUMN #{quoted_column_name} TYPE #{column.sql_type}"

            options = column_options(column)

            if options[:collation]
              change_column_sql << " COLLATE \"#{options[:collation]}\""
            end

            if options[:using]
              change_column_sql << " USING #{options[:using]}"
            elsif options[:cast_as]
              cast_as_type = type_to_sql(options[:cast_as], **options)
              change_column_sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
            end

            if options.key?(:default)
              if options[:default].nil?
                change_column_sql << ", ALTER COLUMN #{quoted_column_name} DROP DEFAULT"
              else
                quoted_default = quote_default_expression(options[:default], column)
                change_column_sql << ", ALTER COLUMN #{quoted_column_name} SET DEFAULT #{quoted_default}"
              end
            end

            if options.key?(:null)
              change_column_sql << ", ALTER COLUMN #{quoted_column_name} #{options[:null] ? 'DROP' : 'SET'} NOT NULL"
            end

            change_column_sql
          end