The following bug has been logged on the website:
Bug reference: 13492
Logged by: Ismael Bezerra
Email address: ismaelbezerra@gmail.com
PostgreSQL version: 9.4.4
Operating system: Linux CentOS 6
Description:
I'm having problem to drop a database. When performing the drop database
command postgresql does not release the disk space. The directory with oid
database remains on disk. This database has been updated from version 9.3.4
to 9.4.4 with the -k option pg_upgrade. What can it be?