1) Create an ordering index on a particular attribute.
2) Create several hundred thousand objects that have that attribute.
3) Perform a paged search with the filter: "(attribute>=\00)" and a server side sort control on the attribute.
Return all the objects that have the attribute in sorted order.
The search fails with the error message: "The search results cannot be sorted because the given search request is not indexed."
It appears that even though there is an index on this attribute, the search code is written to ignore the index for queries that return more than 100000 entries.
If I understand the source code correctly:
org.opends.server.backends.jeb.Index has a cursorEntryLimit parameter that controls the maximum number of results that may be returned by the index.
But this parameter is not configurable. It is always hardcoded to 100000 in org.opends.server.backends.jeb.AttributeIndex