disable synchronous commits

http://www.postgresql.org/docs/current/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT

roles/postgresql/handlers/main.yml

@@ -0,0 +1,4 @@
+---
+- name: restart postgresql
+  service: name=postgresql.service state=restarted
+  when: postgresql is defined and postgresql.enable is defined and postgresql.enable == True

roles/postgresql/tasks/main.yml

@@ -10,6 +10,14 @@
   become: yes
   become_user: postgres
 
+- name: Disable synchronous commits
+  lineinfile: dest=/var/lib/postgres/data/postgresql.conf
+              regexp=^synchronous_commit
+              state=present
+              line="synchronous_commit = off"
+  notify:
+    - restart postgresql
+
 - name: Disable and stop PostgreSQL
   service: name=postgresql.service enabled=no state=stopped
   when: postgresql is not defined or postgresql.enable is not defined or postgresql.enable != True