Planner (find_usable_indexes function, actually) could push pathkey expression into restriction clauses of index. I'm not fully satisfied with this piece of code, but, may be, someone has a better idea. I though about adding separate indexorderquals in IndexPath structure...
Done, IndexScan and IndexPath have separate field to store order clauses. That's allowed to improve explain output:
# EXPLAIN (COSTS OFF)SELECT * FROM point_tbl WHERE f1 <@ '(-10,-10),(10,10)':: box ORDER BY f1 <-> '0,1';
QUERY PLAN
------------------------------------------------
Index Scan using gpointind on point_tbl
Index Cond: (f1 <@ '(10,10),(-10,-10)'::box)
Sort Cond: (f1 <-> '(0,1)'::point)
(3 rows)We are waiting feedback to choose a way of planner support of knn-search. Still TODO: - cost of index scan - Sort condition should not be ANDed in explain output- current patch remove support of IndexScanDesc->kill_prior_tuple, it's needed to restore support if it will not create too big overhead
- documentation
--
Teodor Sigaev E-mail: teo...@sigaev.ru
WWW: http://www.sigaev.ru/
builtin_knngist-0.4.1.gz
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