postgres: Postgres-XC: must start as either a Coordinator (--coordinator) or Datanode (--datanode)

Postgresql Server Error in Ubuntu :
postgres: Postgres-XC: must start as either a Coordinator (--coordinator) or Datanode (--datanode)

To remove this error, remove the package

apt-get --purge remove postgres-xc

But if you are not able to remove it because of an error, Find all processes of postgres using

ps aux | grep postgres
or
ps aux | grep psql

and kill all one by one. Now try to remove again.

Now install these packages:

apt-get install postgresql-client-common
apt-get install postgresql-common
apt-get install postgresql-9.3
apt-get install postgresql-client-9.3
apt-get install postgresql-contrib-9.3