Ranker plugins let you implement a custom ranker that receives all the occurrences of the keywords matched in the document, and computes a WEIGHT() value. They can be called as follows:
SELECT id, attr1 FROM test WHERE match('hello') OPTION ranker=myranker('option1=1');The call workflow is as follows:
XXX_init() gets called once per query per table, in the very beginning. A few query-wide options are passed to it through a SPH_RANKER_INIT structure, including the user options strings (in the example just above, “option1=1” is that string).XXX_update() gets called multiple times per matched document, with every matched keyword occurrence passed as its parameter, a SPH_RANKER_HIT structure. The occurrences within each document are guaranteed to be passed in the order of ascending hit->hit_pos values.XXX_finalize() gets called once per matched document, once there are no more keyword occurrences. It must return the WEIGHT() value. This is the only mandatory function.XXX_deinit() gets called once per query, in the very end.