Hello,
Be sure that the bugs reported in the official bug tracker are read, but it takes time to take them into consideration by the development team.
Please also read the following recent announcement:
My first impression after reading your report is that this issue is not related to Orthanc, but rather to an inappropriate configuration of your PostgreSQL server. Check for instance this discussion:
Maybe someone in this discussion group has better knowledge of the system administration of PostgreSQL than me, and could give initial directions to help and resolve your problem.
Sébastien-