在尝试安装Ambari 2.4时，我收到以下错误。
root@ishanNode1:~# apt-get install ambari-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
ambari-server : Depends: postgresql (>= 8.1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
我安装了postgresql，因为它默认安装在Ubuntu
中root@ishanNode1:~# service postgresql status
● postgresql.service - PostgreSQL RDBMS
Loaded: loaded (/lib/systemd/system/postgresql.service; disabled; vendor preset: enabled)
Active: active (exited) since Fri 2018-02-16 00:01:58 IST; 16s ago
Process: 5847 ExecStart=/bin/true (code=exited, status=0/SUCCESS)
Main PID: 5847 (code=exited, status=0/SUCCESS)
Feb 16 00:01:58 ishanNode1 systemd[1]: Starting PostgreSQL RDBMS...
Feb 16 00:01:58 ishanNode1 systemd[1]: Started PostgreSQL RDBMS.
请告诉我如何解决这个问题。