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    PolarDB:ST_append

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    PolarDB:ST_append

    Last Updated:Mar 28, 2026

    Appends trajectory points or a sub-trajectory to a trajectory object.

    Syntax

    trajectory ST_append(trajectory traj, geometry spatial, timestamp[] timespan, text str_attrs_json);
trajectory ST_append(trajectory traj, trajectory tail);

    The first overload appends individual trajectory points defined by geometry, timestamps, and attributes. The second overload appends an entire sub-trajectory.

    Parameters

    ParameterDescription
    trajThe original trajectory object.
    spatialThe geometry of the trajectory points to append.
    timespanThe timestamp array for the appended points. Can be a timeline.
    str_attrs_jsonThe attributes of the appended points, in JSON format. For the JSON schema, see ST_makeTrajectory.
    tailThe sub-trajectory to append.

    Examples

    Append a sub-trajectory (second overload)

    This example builds two trajectory objects and appends the second to the first using the tail overload. Each trajectory has type STPOINT, three spatial points (LINESTRING), five attributes, and three events.

    WITH traj AS (
  SELECT
    ST_makeTrajectory('STPOINT', 'LINESTRING(1 1, 6 6, 9 8)'::geometry,
      '[2010-01-01 11:30, 2010-01-01 15:00)'::tsrange,
      '{"leafcount":3,"attributes":{"velocity":{"type":"integer","length":2,"nullable":true,"value":[120,130,140]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[120,130,140]},"bearing":{"type":"float","length":8,"nullable":false,"value":[120,130,140]},"acceleration":{"type":"string","length":20,"nullable":true,"value":["120","130","140"]},"active":{"type":"timestamp","nullable":false,"value":["Fri Jan 01 14:30:00 2010","Fri Jan 01 15:00:00 2010","Fri Jan 01 15:30:00 2010"]}},"events":[{"1":"Fri Jan 01 14:30:00 2010"},{"2":"Fri Jan 01 15:00:00 2010"},{"3":"Fri Jan 01 15:30:00 2010"}]}'
    ) a,
    ST_makeTrajectory('STPOINT', 'LINESTRING(7 7, 3 4, 1 5)'::geometry,
      '[2010-01-02 15:30, 2010-01-02 18:00)'::tsrange,
      '{"leafcount":3,"attributes":{"velocity":{"type":"integer","length":2,"nullable":true,"value":[121,131,141]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[121,131,141]},"bearing":{"type":"float","length":8,"nullable":false,"value":[121,131,141]},"acceleration":{"type":"string","length":20,"nullable":true,"value":["121","131","141"]},"active":{"type":"timestamp","nullable":false,"value":["Fri Jan 02 14:30:00 2010","Fri Jan 02 15:00:00 2010","Fri Jan 02 15:30:00 2010"]}},"events":[{"1":"Fri Jan 02 14:30:00 2010"},{"2":"Fri Jan 02 15:00:00 2010"},{"3":"Fri Jan 02 15:30:00 2010"}]}'
    ) b
)
SELECT ST_append(a, b) FROM traj;

    The result is a merged trajectory with leafcount=6, covering the combined spatial path and time range:

    {"trajectory":{"version":1,"type":"STPOINT","leafcount":6,"start_time":"2010-01-01 11:30:00","end_time":"2010-01-02 18:00:00","spatial":"LINESTRING(1 1,6 6,9 8,7 7,3 4,1 5)","timeline":["2010-01-01 11:30:00","2010-01-01 13:15:00","2010-01-01 15:00:00","2010-01-02 15:30:00","2010-01-02 16:45:00","2010-01-02 18:00:00"],"attributes":{"leafcount":6,"velocity":{"type":"integer","length":2,"nullable":true,"value":[120,130,140,121,131,141]},"accuracy":{"type":"float","length":4,"nullable":false,"value":[120.0,130.0,140.0,121.0,131.0,141.0]},"bearing":{"type":"float","length":8,"nullable":false,"value":[120.0,130.0,140.0,121.0,131.0,141.0]},"acceleration":{"type":"string","length":20,"nullable":true,"value":["120","130","140","121","131","141"]},"active":{"type":"timestamp","length":8,"nullable":false,"value":["2010-01-01 14:30:00","2010-01-01 15:00:00","2010-01-01 15:30:00","2010-01-02 14:30:00","2010-01-02 15:00:00","2010-01-02 15:30:00"]}},"events":[{"1":"2010-01-01 14:30:00"},{"2":"2010-01-01 15:00:00"},{"3":"2010-01-01 15:30:00"},{"1":"2010-01-02 14:30:00"},{"2":"2010-01-02 15:00:00"},{"3":"2010-01-02 15:30:00"}]}}

    Key observations:

    • leafcount increases from 3 to 6 — all points from both trajectories are merged.

    • spatial becomes LINESTRING(1 1,6 6,9 8,7 7,3 4,1 5) — the path segments are concatenated in order.

    • timeline spans from 2010-01-01 11:30:00 to 2010-01-02 18:00:00 — timestamps from both trajectories are preserved.

    • Attribute arrays for all five fields are concatenated in order.

    • Events from both trajectories are preserved in the merged result.

    See also