In AllPartial mode, the Oracle Endeca Server first uses All mode to return results matching all search terms, if any are available.
If no such All results are available, the Oracle Endeca Server returns the results that Partial would have produced. This allows a more conservative matching policy than Partial, because high-quality conjunctive results are returned if they exist and Partial results are used as a fallback on conjunctive misses.
This behavior, however, can be affected if cross-field matches are applied to the search interface. A search that matches "any" or "partial" inside of the same field might be returned before a search that matches "all" of the terms but has to cross field boundaries to do so.
In addition, spelling correction can also alter the results. A search that matches any or partial spell-corrected terms in the same field may return before a non-spell-corrected search that matches all terms in different fields. To the user, this looks like there were no records matching all of the terms, even though there may be many that match cross-field.