在狮身人面像中使用通配符时，如何提高精确匹配结果的相关性？

Question

This is my search request:

    (new SphinxSearch())
        ->search((new SphinxClient())->escapeString($query) . '*', 'services')
        ->setMatchMode(SphinxClient::SPH_MATCH_EXTENDED)
        ->setFieldWeights([
            'name' => 10,
            'legal_name' => 10,
            'description' => 10,
            'keywords' => 10,
            'category_name' => 3,
            'categories' => 3,
        ])
        ->setSortMode(SphinxClient::SPH_SORT_EXTENDED, "@weight DESC")
        ->setRankingMode(SphinxClient::SPH_RANK_SPH04)
        ->get(true);

And here is index config:

index services
{
    source = services
    path = /var/lib/sphinxsearch/data/services
    docinfo = extern
    morphology = stem_enru
    min_stemming_len = 1
    min_word_len = 1
    min_infix_len = 1
    html_strip = 1
    index_exact_words = 1
    expand_keywords = 1
    mlock = 0
    charset_table = 0..9, A..Z->a..z, _, *, -, a..z, \
                        U+2C->U+2E, U+2E, U+0044, U+0046, U+0130, U+0401->U+0435, U+0451->U+0435, U+410..U+42F->U+430..U+44F, U+430..U+44F
}

For a query " school №4 " it returns all relevant results, but with something like " school №42 " at the top and the exact match of " school №4 " is close to the bottom of the result set.
Well, it's not actually an exact match - in the service name there may be some other words and symbols. But it's closest to what user entered in the search field, so I believe it should be more relevant than results with a wild card.

How can I move "exact" match to the top of the set?

PS I'm using this Laravel specific wrapper for SphinxClient, though I don't think it's important.

Answer 1

One option could, try the expand_keywords option http://sphinxsearch.com/docs/current.html#conf-expand-keywords

can possibly improve the search quality, as the documents with exact form matches should be ranked generally higher than documents with stemmed or infix matches.

Alas it's a index level config, rather than query. Can then remove the * from the query.

Answer 2

Current solution that I have - make two queries with and without wildcard and then merge results with exact matches on the top. It works, but not ideal, obviously.