The search extension functions complement the Search Built-in functions.
xdmp:diacritic-less("José") => Jose
cts:search()
xdmp:estimate
xdmp:query-trace()
unsearchable
xdmp:estimate(collection()) => 10476
Queries that use xdmp:exists require that the XPath expression searched is partially searchable. A partially searchable XPath expression is one whose first step is searchable. You can use xdmp:query-trace() to determine if a step is searchable. If there are no entries in the xdmp:query-trace() output indicating that the first step is unsearchable, then the expression is partially searchable and you can perform an xdmp:exists operation on it.
xdmp:exists
Calling xdmp:exists on an expression is the same as calling xdmp:estimate on the expression with a maximum of 1. For example, the following are equivalent:
xdmp:exists(cts:search(collection(), "foo")) is equivalent to: xs:boolean(xdmp:estimate(cts:search(collection(), "foo"), 1))
xdmp:exists(collection()) => true
xdmp:request-timestamp
xdmp:eval
xdmp:request-timestamp() => 1234567