Re: BUG #12578: row_to_json() and to_json() add 'T' in timestamp field.

yoonghm@gmail.com writes:
> row_to_json and to_json replace the space between date and time.

This is not a bug; it's an intentional behavioral change.  Per the
third bullet point in the 9.4 release notes:

* When converting values of type date, timestamp or timestamptz to JSON,
  render the values in a format compliant with ISO 8601 (Andrew Dunstan)

  Previously such values were rendered according to the current DateStyle
  setting; but many JSON processors require timestamps to be in ISO 8601
  format. If necessary, the previous behavior can be obtained by
  explicitly casting the datetime value to text before passing it to the
  JSON conversion function.


            regards, tom lane