diff --git a/vars/default_vars.yml b/vars/default_vars.yml
index e26771b47..3a66c47d4 100644
--- a/vars/default_vars.yml
+++ b/vars/default_vars.yml
@@ -284,9 +284,11 @@ squid_enabled: False
 dansguardian_install: False
 dansguardian_enabled: False
 
-# PostgreSQL auto-installed by Moodle &/or Pathagar as nec, no need to touch!
-# roles/1-prep/tasks/computed_vars.yml, roles/4-server-options/tasks/main.yml
-postgresql_install: False
+# 2020-01-23: postgresql_install is completely ignored as PostgreSQL is
+# installed on demand as a dependency -- by Moodle &/or Pathagar as nec --
+# but for now we set fake value 'postgresql_install: True' for
+# 'postgresql_installed is defined' tests e.g. in 0-init/tasks/validate_vars.yml
+postgresql_install: True
 postgresql_enabled: False
 
 # Common UNIX Printing System (CUPS)
@@ -379,6 +381,12 @@ mosquitto_install: False
 mosquitto_enabled: False
 mosquitto_port: 1883
 
+# 2020-01-23: nodejs_install is completely ignored as Node.js is installed on
+# demand as a dependency -- by Node-RED, Sugarizer and/or Internet Archive --
+# but for now we set fake value 'nodejs_install: True' for
+# 'nodejs_installed is defined' tests e.g. in 0-init/tasks/validate_vars.yml
+nodejs_install: True
+nodejs_enabled: False
 # Node.js version used by roles/nodejs/tasks/main.yml for 3 roles:
 # nodered (Node-RED), pbx (Asterix, FreePBX) & sugarizer (Sugarizer)
 nodejs_version: 12.x    # was 8.x until 2019-02-02, was 10.x until 2019-12-21
@@ -445,18 +453,18 @@ moodle_install: False
 moodle_enabled: False
 # If using Moodle intensively, set apache_high_php_limits in 3-BASE-SERVER
 
-# MongoDB (/library/dbdata/mongodb) is used by Sugarizer:
-# The mongodb playbook itself is later invoked by roles/sugarizer/meta/main.yml
-# 2019-07-08: mongodb_install is completely ignored as it is installed on demand as a dependency.
-# 2020-01-23 set to True for installed: True test
+# MongoDB (/library/dbdata/mongodb) greatly enhances the Sugarizer experience.
+# The roles/mongodb playbook (was?) invoked by roles/sugarizer/meta/main.yml
+# 2020-01-23: mongodb_install is completely ignored as MongoDB is installed on
+# demand as a dependency -- by Sugarizer -- but for now we set fake value
+# 'mongodb_install: True' for 'mongodb_installed is defined' tests e.g. in
+# 0-init/tasks/validate_vars.yml
 mongodb_install: True
-
-# FYI mongodb_enabled: False works but is ineffective but is required by mongodb/tasks/enable.yml
-# to shutdown the service and log status but that is misleading as Sugarizer starts mongodb's systemd
-# svc on its own due to requires=mongodb.service within sugarizer.service file
+# FYI 'mongodb_enabled: False' works but is ineffective.  Required by
+# mongodb/tasks/enable.yml to shut down the service and log status, but that is
+# misleading as Sugarizer starts mongodb's systemd service on its own, due to
+# 'Requires=mongodb.service' within /etc/systemd/system/sugarizer.service
 mongodb_enabled: False
-
-# port assignment
 mongodb_port: 27018
 
 # Regional OSM vector maps use far less disk space than bitmap/raster versions.