MarkLogic 9 Product Documentation

fn:distinct-nodes

fn:distinct-nodes(
   $nodes as node()*
) as node()*

Summary

[0.9-ml only] Returns the sequence resulting from removing from the input sequence all but one of a set of nodes that have the same identity as one another. If the empty sequence is input, fn:distinct-nodes returns the empty sequence.

Usage Notes

Note that for a node to have the same identity as another node, it must be exactly the same node (not an equivalent node). For example, for a node bound to the variable $x to have the same identity as a node bound to the variable $y, the following must return true:

$x is $y

Example

  (:
    assume /mydoc.xml has the following contents:
    <a>hello</a>
  :)

  let $x := fn:doc("/mydoc.xml")/a
  let $y := /a
  return
  fn:distinct-nodes(($x, $y))

=> <a>hello</a>

Example

  (:
    assume /mydoc.xml has the following contents:
    <a>hello</a>
  :)

  let $x := fn:doc("/mydoc.xml")/a
  let $y := <a>hello</a>
  return
  fn:distinct-nodes(($x, $y))

=> (<a>hello</a>, <a>hello</a>)
   It returns both nodes because they do not
   have the same identity.