diff --git a/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml b/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
index e9929f96e..6cabea3ec 100644
--- a/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
+++ b/roles/matrix-bridge-mautrix-whatsapp/defaults/main.yml
@@ -27,6 +27,42 @@ matrix_mautrix_whatsapp_systemd_wanted_services_list: []
 matrix_mautrix_whatsapp_appservice_token: ''
 matrix_mautrix_whatsapp_homeserver_token: ''
 
+
+# Database-related configuration fields.
+#
+# To use SQLite, stick to these defaults.
+#
+# To use Postgres:
+# - change the engine (`matrix_mautrix_whatsapp_database_engine: 'postgres'`)
+# - adjust your database credentials via the `matrix_mautrix_whatsapp_postgres_*` variables
+matrix_mautrix_whatsapp_database_engine: 'sqlite'
+
+matrix_mautrix_whatsapp_sqlite_database_path_local: "{{ matrix_mautrix_whatsapp_data_path }}/mautrix-whatsapp.db"
+matrix_mautrix_whatsapp_sqlite_database_path_in_container: "/data/mautrix-whatsapp.db"
+
+matrix_mautrix_whatsapp_postgres_username: 'matrix_mautrix_whatsapp'
+matrix_mautrix_whatsapp_postgres_password: 'some-password'
+matrix_mautrix_whatsapp_postgres_hostname: 'matrix-postgres'
+matrix_mautrix_whatsapp_postgres_port: 5432
+matrix_mautrix_whatsapp_postgres_db_name: 'matrix_mautrix_whatsapp'
+
+matrix_mautrix_whatsapp_postgres_connection_string: 'postgresql://{{ matrix_mautrix_whatsapp_postgres_username }}:{{ matrix_mautrix_whatsapp_postgres_password }}@{{ matrix_mautrix_whatsapp_postgres_hostname }}:{{ matrix_mautrix_whatsapp_postgres_port }}/{{ matrix_mautrix_whatsapp_postgres_db_name }}'
+
+matrix_mautrix_whatsapp_appservice_database_type: "{{
+	{
+		'sqlite': 'sqlite3',
+		'postgres':'postgres',
+	}[matrix_mautrix_whatsapp_database_engine]
+}}"
+
+matrix_mautrix_whatsapp_appservice_database_uri: "{{
+	{
+		'sqlite': matrix_mautrix_whatsapp_sqlite_database_path_in_container,
+		'postgres': matrix_mautrix_whatsapp_postgres_connection_string,
+	}[matrix_mautrix_whatsapp_database_engine]
+}}"
+
+
 # Can be set to enable automatic double-puppeting via Shared Secret Auth (https://github.com/devture/matrix-synapse-shared-secret-auth).
 matrix_mautrix_whatsapp_login_shared_secret: ''
 
diff --git a/roles/matrix-bridge-mautrix-whatsapp/tasks/setup_install.yml b/roles/matrix-bridge-mautrix-whatsapp/tasks/setup_install.yml
index 6bd87bbe2..15453e8ca 100644
--- a/roles/matrix-bridge-mautrix-whatsapp/tasks/setup_install.yml
+++ b/roles/matrix-bridge-mautrix-whatsapp/tasks/setup_install.yml
@@ -8,6 +8,26 @@
       The matrix-bridge-mautrix-whatsapp role needs to execute before the matrix-synapse role.
   when: "matrix_synapse_role_executed|default(False)"
 
+- block:
+  - name: Check if an SQLite database already exists
+    stat:
+      path: "{{ matrix_mautrix_whatsapp_sqlite_database_path_local }}"
+    register: matrix_mautrix_whatsapp_sqlite_database_path_local_stat_result
+
+  - name: Fail if an SQLite database already exists when using Postgres
+    fail:
+      msg: >-
+        matrix_mautrix_whatsapp_database_engine has been set to `postgres` (which is our new default now).
+        However, we've discovered an existing SQLite database in {{ matrix_mautrix_whatsapp_sqlite_database_path_local }}.
+        It appears that you've been using this bridge with the SQLite engine until now.
+        To continue using SQLite, opt into it explicitly: add `matrix_mautrix_whatsapp_database_engine: sqlite` to your vars.yml file and re-run this same command.
+        Alternatively, to migrate your existing SQLite database to Postgres:
+        1. Stop all services (`ansible-playbook -i inventory/hosts setup.yml --tags=stop`)
+        2. Import the SQLite database into Postgres (`ansible-playbook -v -i inventory/hosts setup.yml --tags=import-generic-sqlite-db --extra-vars='sqlite_database_path={{ matrix_mautrix_whatsapp_sqlite_database_path_local }} postgres_connection_string_variable_name=matrix_mautrix_whatsapp_postgres_connection_string'`)
+        3. Re-run the playbook (`ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start`)
+    when: "matrix_mautrix_whatsapp_sqlite_database_path_local_stat_result.stat.exists"
+  when: "matrix_mautrix_whatsapp_database_engine == 'postgres'"
+
 - name: Ensure Mautrix Whatsapp image is pulled
   docker_image:
     name: "{{ matrix_mautrix_whatsapp_docker_image }}"
@@ -26,12 +46,12 @@
     - "{{ matrix_mautrix_whatsapp_base_path }}"
     - "{{ matrix_mautrix_whatsapp_config_path }}"
     - "{{ matrix_mautrix_whatsapp_data_path }}"
-    
+
 - name: Check if an old database file exists
   stat:
     path: "{{ matrix_mautrix_whatsapp_base_path }}/mautrix-whatsapp.db"
   register: matrix_mautrix_whatsapp_stat_database
-  
+
 - name: Check if an old matrix state file exists
   stat:
     path: "{{ matrix_mautrix_whatsapp_base_path }}/mx-state.json"
@@ -48,7 +68,7 @@
 - name: (Data relocation) Move mautrix-whatsapp database file to ./data directory
   command: "mv {{ matrix_mautrix_whatsapp_base_path }}/mautrix-whatsapp.db {{ matrix_mautrix_whatsapp_data_path }}/mautrix-whatsapp.db"
   when: "matrix_mautrix_whatsapp_stat_database.stat.exists"
-  
+
 - name: (Data relocation) Move mautrix-whatsapp mx-state file to ./data directory
   command: "mv {{ matrix_mautrix_whatsapp_base_path }}/mx-state.json {{ matrix_mautrix_whatsapp_data_path }}/mx-state.json"
   when: "matrix_mautrix_whatsapp_stat_mx_state.stat.exists"
diff --git a/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2 b/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
index 93956049c..892166956 100644
--- a/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
+++ b/roles/matrix-bridge-mautrix-whatsapp/templates/config.yaml.j2
@@ -19,11 +19,11 @@ appservice:
     # Database config.
     database:
         # The database type. "sqlite3" and "postgres" are supported.
-        type: sqlite3
+        type: {{ matrix_mautrix_whatsapp_appservice_database_type|to_json }}
         # The database URI.
         #   SQLite: File name is enough. https://github.com/mattn/go-sqlite3#connection-string
         #   Postgres: Connection string. For example, postgres://user:password@host/database
-        uri: postgres://matrix_bridge_whatsapp@{{ matrix_additional_databases | selectattr('name', 'equalto', 'matrix_bridge_whatsapp') | map(attribute='pass') | first }}@{{ matrix_postgres_connection_hostname }}/matrix_bridge_whatsapp
+        uri: {{ matrix_mautrix_whatsapp_appservice_database_uri|to_json }}
         # Maximum number of connections. Mostly relevant for Postgres.
         max_open_conns: 20
         max_idle_conns: 2