MarkLogic: Understanding searchable and unsearchable queries?

Question

I have the following expression:

let $q1 := cts:element-range-query(xs:QName("ts:week"), ">=" ,xs:date("2009-04-25"))
return cts:search(fn:doc(), $q1, "unfiltered")

I did a xdmp:plan, and got to know that range indexes are being used and the expression is searchable

However, when I added a XPath:

let $q1 := cts:element-range-query(xs:QName("ts:week"), ">=" ,xs:date("2009-04-25"))
return cts:search(fn:doc(), $q1, "unfiltered")/ts:top-song/ts:title/text()

On doing a xdmp:plan, it told me the path is unsearchable. Further on doing in query-trace it said other than fn:doc() nothing searchable.

However, since I am getting the correct result. My guess is that indexes are working just fine.

If so, what is logging the message "unsearchable" ?

I specifically need the title element in this case, is there anything I can do to make the entire expression searchable ?

Answer 1

This code is doing two things:

• Executing a search to get a sequence of documents
• Applying an XPath to the sequence of documents to extract nodes from the documents

To put it another way, the XPath is not part of the search. It applies post-processing to the results of the search.

Both xdmp:estimate() and xdmp:plan() accept only the input to the search and not the post-processing on the results of the search.

Hoping that clarifies,

Answer 2

If there were an element range index on the ts:title element, you could use cts:element-values() to retrieve the titles by applying the $q1 query, and that would be an index-resolved operation.

For example:

cts:element-values(xs:QName("ts:title"), "", (), $q1)