ST_IsValidTrajectory
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## Name

ST_IsValidTrajectory — Tests if the geometry is a valid trajectory.

## Synopsis

`boolean ST_IsValidTrajectory(`geometry line`)`;

## Description

Tests if a geometry encodes a valid trajectory. A valid trajectory is represented as a `LINESTRING` with measures (M values). The measure values must increase from each vertex to the next.

Valid trajectories are expected as input to spatio-temporal functions like ST_ClosestPointOfApproach

Availability: 2.2.0

This function supports 3d and will not drop the z-index.

## Examples

    -- A valid trajectory
    SELECT ST_IsValidTrajectory(ST_MakeLine(
      ST_MakePointM(0,0,1),
      ST_MakePointM(0,1,2))
    );
     t

    -- An invalid trajectory
    SELECT ST_IsValidTrajectory(ST_MakeLine(ST_MakePointM(0,0,1), ST_MakePointM(0,1,0)));
    NOTICE:  Measure of vertex 1 (0) not bigger than measure of vertex 0 (1)
     st_isvalidtrajectory
    ----------------------
     f

## See Also

ST_ClosestPointOfApproach

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