For the near operator, the score is based upon the physical proximity of the search terms in the document, not how often the search terms occur. A document where both search terms are immediately adjacent scores 100. Where two search terms occur in a document, and may return a much lower score than near if the two search terms are in close proximity to each other. With and or or the query may have returned exactly what you are looking for, but the score may be low because the search terms had a low level of occurrence. For a query combining either and or or, with near , the score is ambiguous.
Maximum records limits size of the result set.
A maximum of 1000 has been arbitrarily chosen to prevent retrieval of an overly large result set. The size of the result set will depend upon the setting of both maximum records and threshold score. The National Library of Canada.