The following bug has been logged on the website:
Bug reference: 12989
Logged by: Christian Almeida
Email address: cbalmeida(at)gmail(dot)com
PostgreSQL version: 9.3.6
Operating system: Ubuntu 14.04 LTS
Description:
The function "pg_size_pretty" is not formatting negative numbers.
Example:
select pg_size_pretty(+123456789::bigint),
pg_size_pretty(-123456789::bigint)
Output:
----------------------------
118 MB -123456789 bytes