Simplify a jql for a board

[Joe]

I am trying to simplify a query for board to show all the child issues for an epic. 

project in ("P") AND issue in childIssuesOf(P-1) OR issue in childIssuesOf(P-2) OR issue in childIssuesOf(P-3) OR issue in childIssuesOf(P-4) OR issue in childIssuesOf(P-5) OR issue in childIssuesOf(P-6) ORDER BY Rank


Any suggestions? 

[Sudarshan]

Hello @Joe try 

project = P AND issueFunction in issuesInEpics("issuekey in (epic number)")

 This JQL results out the items linked to the specified epic.

If you are looking for the hierarchy result -- not possible with JQL - try with Structures.