This update for postgresql94 to 9.4.19 fixes the following security issue:
A dump/restore is not required for this update unless you use the functions querytoxml, cursortoxml, cursortoxmlschema, querytoxmlschema, and querytoxmlandxmlschema. In this case please see the first entry of https://www.postgresql.org/docs/9.4/static/release-9-4-18.html