With indexes added in the search_simpledb_index table in MDL-70870, the ordering of search results are not quite predictable anymore as the sort order now depends on the index order and can cause the \core_search\top_result_test unit test to fail (especially in Oracle).

As such, we had to apply ordering in \search_simpledb\engine::execute_query(). I think though that we shouldn't have to do this and perhaps better to look into rewriting top_result_test (or parts of it) in a way to test search results ranking without relying on the ordering of the results.