Check_MK Werk 5753: mk_postgres: reduce the amount of psql sessions opened by the plugin

ID: 5753 Title: mk_postgres: reduce the amount of psql sessions opened by the plugin Component: Checks & agents Level: 1 Class: New feature Version: 1.5.0i4 Previously, the number of psql sessions scaled linearly with the number of databases. Now the number of psql sessions opened by the plugin is constant. Additionally, the sessions of some sections were combined to further reduce the total number of psql sessions.