The number of exact_nb_hits
seen in a Query Suggestions (QS) record corresponds to the number of hits that suggestion returns in the source index with a strict search applied.
This "strict" search, performed by the engine, uses a set of predefined query parameters (e.g., without prefix-search, typo-tolerance, etc.) that override any query parameters you have configured and therefore returns different results than those seen in a "normal" search.
As a result, if you search for a suggestion in your source index, you will notice a difference in nbhits
vs exact_nb_hit
in the QS record for that suggestion. This discrepancy is due to the strict search the QS index builder uses to get the exact_nb_hit
count.
The strict search is designed to ensure a query returns enough relevant results, containing only the exact query, to be added to the QS index. You can configure the minimum number of hits required for a query to be added to your QS index from your Query Suggestions index’s configuration page.