使用PostGIS查找给定2点的最近线？

我有一个表t，其中包含一列line_positionsline类型的列。给定2个点，我想找到最接近的直线，该直线足够接近（小于10公里）并且距离我想要避免的点（最小20公里）的距离不太远。目前我使用

SELECT t.*
FROM path t
WHERE
  ST_DWithin(ST_GeographyFromText('Point(69.835 22.596)'), t.line_positions, 10000, FALSE)  AND
  ST_DWithin(ST_GeographyFromText('Point(69.856 22.519)'), t.line_positions, 10000, false) AND
  NOT ST_DWithin(ST_GeographyFromText('Point(-79.804 9.141)'), t.line_positions, 20000, false)
ORDER BY
  ST_Distance(ST_GeographyFromText('Point(69.835 22.576)'), t.line_positions, false) +
  ST_Distance(ST_GeographyFromText('Point(69.856 22.519)'), t.line_positions, false)
  ASC
LIMIT 1

ix_path_line_positionsline_positions列上有一个要点索引。

它有效，但速度很慢，在t中仅100000行在3s到30s之间。

解释分析给出：

Limit  (cost=9.95..9.95 rows=1 width=1432) (actual time=21729.253..21729.254 rows=1 loops=1)
   ->  Sort  (cost=9.95..9.95 rows=1 width=1432) (actual time=21729.251..21729.251 rows=1 loops=1)
         Sort Key: ((_st_distance('0101000020E61000003D0AD7A370755140FA7E6ABC74933640'::geography, line_positions, '0'::double precision, false) + _st_distance('0101000020E6100000105839B4C8765140BE9F1A2FDD843640'::geography, line_positions, '0'::double precision, false)))
         Sort Method: top-N heapsort  Memory: 26kB"
         ->  Index Scan using ix_path_line_positions on path t  (cost=0.28..9.94 rows=1 width=1432) (actual time=93.490..21710.562 rows=690 loops=1)
           Index Cond: ((line_positions && '0101000020E61000003D0AD7A3707551407F6ABC7493983640'::geography) AND (line_positions && '0101000020E6100000105839B4C8765140BE9F1A2FDD843640'::geography))
           Filter: (('0101000020E61000003D0AD7A3707551407F6ABC7493983640'::geography && _st_expand(line_positions, '10000'::double precision)) AND ('0101000020E6100000105839B4C8765140BE9F1A2FDD843640'::geography && _st_expand(line_positions, '10000'::double precision)) AND _st_dwithin('0101000020E61000003D0AD7A3707551407F6ABC7493983640'::geography, line_positions, '10000'::double precision, false) AND _st_dwithin('0101000020E6100000105839B4C8765140BE9F1A2FDD843640'::geography, line_positions, '10000'::double precision, false) AND ((NOT ('0101000020E6100000FA7E6ABC74F353C0D578E92631482240'::geography && _st_expand(line_positions, '20000'::double precision))) OR (NOT (line_positions && '0101000020E6100000FA7E6ABC74F353C0D578E92631482240'::geography)) OR (NOT _st_dwithin('0101000020E6100000FA7E6ABC74F353C0D578E92631482240'::geography, line_positions, '20000'::double precision, false))))
           Rows Removed by Filter: 15365
Planning time: 0.491 ms
Execution time: 21729.321 ms

我该如何改善？改用几何计算（但是我的轨迹可能跨越数千公里，计算出的距离是否正确）？使用<-> KNN运算符（但由于我对2个距离的和进行排序，所以无论如何似乎都没有使用gist索引）？

两个给定的点是否始终在10公里之内？如果是这样，您可以尝试将两点做成一条直线，然后执行一个ST_DWithin而不是两个。这可能会稍微改善。

SELECT t.*
FROM path t
WHERE
  ST_DWithin(ST_GeomFromText('LINESTRING(69.835 22.596,69.856 22.519)'), t.line_positions, 10000, FALSE)  
  NOT ST_DWithin(ST_GeographyFromText('Point(-79.804 9.141)'), t.line_positions, 20000, false)
ORDER BY
  ST_Distance(ST_GeographyFromText('Point(69.835 22.576)'), t.line_positions, false) +
  ST_Distance(ST_GeographyFromText('Point(69.856 22.519)'), t.line_positions, false)
  ASC
LIMIT 1