Written Tutorial

Problem

Someone with access to Query Console, but not to the Admin User Interface, wants to know the names of hosts in the cluster.

Solution

xdmp.hosts().toArray().map(function(host) { return xdmp.hostName(host); });

xdmp:hosts() ! xdmp:host-name(.)

Discussion

The Admin UI provides a lot of information about a MarkLogic cluster: configuration of databases, application servers, groups, and other information. It also provides a means to change all these things. As such, access to it is limited to those who have the “admin” privilege. This permits a user to do anything in MarkLogic, including seeing and updating any data, so this role should be tightly held to an administration team that uses procedures to ensure mistakes don’t happen, especially in production.

Query Console, on the other hand, can be much more widely available. Developers working on a project will likely be able to use Query Console to try out queries. Their rights will likely be limited to what they need, but it doesn’t take much to run Query Console.

Sometimes team members may want to get the list of hostnames in a cluster. This recipe is a simple one-liner, but very useful all the same. xdmp:hosts() returns the IDs of all hosts in the cluster. We then feed those values to xdmp:host-name to return the human-readable names.