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When using POSTGResql and POINT type / GIST indexing for LOCATIOn querIEs,"liMIT" clause is required for correctly utilizing the GIST index.
create table points ( name varchar(40) NOT NULL,type varchar(4) NOT NulL,loc POint nOT NulL ); CREATE INDEX pointdist ON points USING gist (loc); INSERT INTO points (name,type,loC) VALUES ('p1','loc',point '(151.192124,-33.888159)'),('p2',point '(151.181696,-33.885665)'); explain SELECT name,loc FROM points ORDER BY point '(151.192124,-33.888159)' <-> loc; explain SELECT name,loc FROM points ORDER BY loc <-> point '(151.192124,-33.888159)' liMIT 10; -- MUST HAVE liMIT TO USE INDEX create table points1 ( name varchar(40) NOT NULL,loc POint nOT NulL ); CREATE INDEX pointdist1 ON points1 USING gist (loc); INSERT INTO points1 (name,loc FROM points1 ORDER BY point '(151.192124,-33.888159)' <-> loc liMIT 10; explain SELECT name,loc FROM points1 ORDER BY loc <-> point '(151.192124,-33.888159)' liMIT 10; query PLAN ------------------------------------------------------------------------------------- limit (cost=0.00..0.99 rows=10 wIDth=114) -> Index Scan using pointdist1 on points1 (cost=0.00..55.45 rows=560 wIDth=114) Order By: (loc <-> '(151.192124,-33.888159)'::point) explain SELECT name,-33.888159)'; query PLAN ------------------------------------------------------------------ Sort (cost=42.56..43.96 rows=560 wIDth=114) Sort Key: ((loc <-> '(151.192124,-33.888159)'::point)) -> Seq Scan on points1 (cost=0.00..17.00 rows=560 wIDth=114)
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