以某出行APP的數(shù)據(jù)為例，其建表語句為：

CREATE TABLE trajectory_table(
    userid numeric PRIMARY KEY, 
    traj trajectory
);

創(chuàng)建軌跡支持多種方式，具體如下：

• 將點表轉(zhuǎn)化為軌跡，具體請參見點表。

  由于執(zhí)行GROUP BY操作時不一定保證點的次序，因此需要調(diào)用ST_Sort()函數(shù)，將軌跡點根據(jù)時間重新排序。

  INSERT INTO trajectory_table
  SELECT userid, ST_Sort(ST_MakeTrajectory(pnts.tjraw, true, '{"intensity"}'::cstring[]))
  FROM
  (SELECT sample_points.userid, 
          array_agg(
              ROW(sample_points.sample_time, 
                  sample_points.x, 
                  sample_points.y, 
                  sample_points.z, 
                  sample_points.intensity)) 
          AS tjraw FROM sample_points GROUP BY userid
  ) pnts;

• ST_makeTrajectory提供多種方式構(gòu)造軌跡：

  說明

  本示例僅展示ID為1的軌跡，通過Geometry類型+時間戳數(shù)組+屬性JSON串構(gòu)造軌跡。

  INSERT INTO trajectory_table 
  SELECT 3, ST_MakeTrajectory(
              'STPOINT'::leaftype, 
              st_geomfromtext('LINESTRING(114.35 39.28 4,114.36 39.28 4,114.35 39.29 4)', 4326), 
              ARRAY['2020-04-11 17:42:30'::timestamp,'2020-04-11 17:43:30'::timestamp,'2020-04-11 17:45:00'::timestamp], 
              '{"leafcount":3,"attributes":{"intensity":{"type":"integer","length":4,"nullable":true,"value":[80,30,50]}}}'
  );           

  說明

  ST_makeTrajectory函數(shù)提供多種方式構(gòu)造軌跡，一些方式需要依賴Ganos的Geometry幾何類型，更多信息，請參見幾何類型。

• JSON字符串構(gòu)建軌跡：

  INSERT INTO trajectory_table
  SELECT 4, 
  '{"trajectory":{"version":1,"type":"STPOINT","leafcount":3,"start_time":"2020-04-11 17:42:30","end_time":"2020-04-11 17:45:00","spatial":"SRID=4326;LINESTRING(114.35 39.28 4,114.36 39.28 4,114.35 39.29 4)","timeline":["2020-04-11 17:42:30","2020-04-11 17:43:30","2020-04-11 17:45:00"],"attributes":{"leafcount":3,"intensity":{"type":"integer","length":4,"nullable":true,"value":[80,30,50]}}}}'
  ::trajectory;

對于整條的軌跡，支持進(jìn)行時空相關(guān)的操作，例如相交、包含的判斷等。通過建立R樹索引，可以加速空間查詢。

--創(chuàng)建索引。
CREATE INDEX ON trajectory_table USING gist(traj);

--查找所有與一個二維矩形范圍相交的軌跡，返回其userid。
SELECT userid FROM trajectory_table WHERE ST_2DIntersects(traj, ST_MakeEnvelope(114.33,39.28,14.331,39.282));