How do I query MarkLogic to determine cost of re-indexing?

Question

I have a multi-terabyte Production database (MarkLogic 9.0-8, RedHat) that I need to add 2 new element range indexes to. Before I can execute the change, I need to get an estimate of the number of documents that will be impacted by the re-index to ensure my maintenance window is sufficient to avoid performance impacts. Will the following code provide me with what I am needing?

xquery version "1.0-ml";

xdmp:estimate(cts:search(fn:doc(), cts:word-query("someTimestamp")));
xdmp:estimate(cts:search(fn:doc(), cts:word-query("someString")));

Answer 1

Instead of a word-query I'd rather count the fragments containing the elements of your two new element range indexes using a element-query.

xdmp:estimate(
  cts:search(fn:doc(), 
    cts:element-query(xs:QName("your-index-element"), (cts:and-query(())))
  )
)