查询：
with bus_points AS (
select osm_id, way from opengeo.ru_psk_point where public_transport='stop_position' and tags -> 'bus' = 'yes'
)
select
id_start,start_way,dist_start,id_end,end_way,dist_end
,(dist_start+dist_end) as sum_dist
from
(select osm_id as id_start, way as start_way, ST_Distance_Spheroid(ST_Transform(way,4326), ST_GeomFromText('POINT(28.2789393 57.8155523)',4326), 'SPHEROID["WGS 84",6378137,298.257223563]') as dist_start from bus_points order by dist_start) t1,
(select osm_id as id_end, way as end_way, ST_Distance_Spheroid(ST_Transform(way,4326), ST_GeomFromText('POINT(28.2951125 57.8141805)',4326), 'SPHEROID["WGS 84",6378137,298.257223563]') as dist_end from bus_points order by dist_end) t2,
opengeo.ru_psk_rels rels
where array[id_start,id_end]<@rels.parts
and array['route','ref']<@rels.tags
and bus_idx_rels_parts(rels.id,id_start)<bus_idx_rels_parts(rels.id,id_end)
order by sum_dist limit 1;
分析：
"Limit (cost=1606.91..1606.91 rows=1 width=96) (actual time=4396.739..4396.745 rows=1 loops=1)"
" CTE bus_points"
" -> Seq Scan on ru_psk_point (cost=0.00..1568.94 rows=1 width=136) (actual time=0.066..17.067 rows=181 loops=1)"
" Filter: ((public_transport = 'stop_position'::text) AND ((tags -> 'bus'::text) = 'yes'::text))"
" Rows Removed by Filter: 24330"
" -> Sort (cost=37.97..37.97 rows=1 width=96) (actual time=4396.710..4396.710 rows=1 loops=1)"
" Sort Key: (((st_distance_spheroid(st_transform(bus_points.way, 4326), '0101000020E6100000B311E39068473C40BB568C0464E84C40'::geometry, 'SPHEROID("WGS 84",6378137,298.257223562997)'::spheroid)) + (st_distance_spheroid(st_transform(bus_points.way, 4326), '0101000020E61000000B24287E8C4B3C403D450E1137E84C40'::geometry, 'SPHEROID("WGS 84",6378137,298.257223562997)'::spheroid))))"
" Sort Method: top-N heapsort Memory: 17kB"
" -> Nested Loop (cost=33.39..37.96 rows=1 width=96) (actual time=40.099..4356.620 rows=4731 loops=1)"
" -> Nested Loop (cost=0.57..0.61 rows=1 width=96) (actual time=32.312..651.802 rows=32761 loops=1)"
" -> Sort (cost=0.28..0.29 rows=1 width=40) (actual time=25.935..27.065 rows=181 loops=1)"
" Sort Key: (st_distance_spheroid(st_transform(bus_points.way, 4326), '0101000020E6100000B311E39068473C40BB568C0464E84C40'::geometry, 'SPHEROID("WGS 84",6378137,298.257223562997)'::spheroid))"
" Sort Method: quicksort Memory: 29kB"
" -> CTE Scan on bus_points (cost=0.00..0.27 rows=1 width=40) (actual time=2.071..24.295 rows=181 loops=1)"
" -> Sort (cost=0.28..0.29 rows=1 width=40) (actual time=0.041..1.184 rows=181 loops=181)"
" Sort Key: (st_distance_spheroid(st_transform(bus_points.way, 4326), '0101000020E61000000B24287E8C4B3C403D450E1137E84C40'::geometry, 'SPHEROID("WGS 84",6378137,298.257223562997)'::spheroid))"
" Sort Method: quicksort Memory: 29kB"
" -> CTE Scan on bus_points (cost=0.00..0.27 rows=1 width=40) (actual time=1.709..4.828 rows=181 loops=1)"
" -> Bitmap Heap Scan on ru_psk_rels rels (cost=32.82..37.34 rows=1 width=86) (actual time=0.092..0.096 rows=0 loops=32761)"
" Recheck Cond: ((ARRAY[bus_points.osm_id, bus_points.osm_id] <@ parts) AND ('{route,ref}'::text[] <@ tags))"
" Filter: (bus_idx_rels_parts(id, bus_points.osm_id) < bus_idx_rels_parts(id, bus_points.osm_id))"
" Rows Removed by Filter: 0"
" -> BitmapAnd (cost=32.82..32.82 rows=1 width=0) (actual time=0.067..0.067 rows=0 loops=32761)"
" -> Bitmap Index Scan on idx_ru_psk_rels_gin_parts (cost=0.00..12.23 rows=31 width=0) (actual time=0.017..0.017 rows=0 loops=32761)"
" Index Cond: (ARRAY[bus_points.osm_id, bus_points.osm_id] <@ parts)"
" -> Bitmap Index Scan on idx_ru_psk_rels_gin_tags (cost=0.00..20.33 rows=44 width=0) (actual time=0.197..0.197 rows=499 loops=5735)"
" Index Cond: ('{route,ref}'::text[] <@ tags)"
"Total runtime: 4397.374 ms"
我只需要一行最少的SUM_DIST。
更多
CREATE OR REPLACE FUNCTION bus_idx_rels_parts(IN bigint, IN bigint, OUT idx integer)
RETURNS integer AS
' SELECT idx from opengeo.ru_psk_rels_parts_idx where id=$1 and unnest=$2 '
LANGUAGE sql VOLATILE
COST 100;
和ORDER BY dist_ *加快时间。
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答案 0 :(得分：0)
对于初学者，您可能需要 format = "( createdBy == %@ && createdTo == %@ ) "
format += " || ( createdBy == %@ && createdTo == %@ ) "
let predicate = NSPredicate(format: format, me!, you, me!, you)
中的索引。这取决于您的查询的性质。如果您始终查询与特定opengeo.ru_psk_point相关的标记，请使用组合的GIN索引：
public_transport如果每种类型的CREATE INDEX ON opengeo.ru_psk_point USING GIN (public_transport, tags);
只有少数几个标签，那么只有该字段的正常索引：
public_transport如果您经常查询许多不同的标记，但不一定与特定的public_transport相关，那么CREATE INDEX ON opengeo.ru_psk_point (public_transport);
上的简单GIN索引：
tags<小时/>
CREATE INDEX ON opengeo.ru_psk_point USING GIN (tags);
是2 x 4,731倍