In Interactive SQL, connect to the sample database execute the following statement to create a variable called arc in which you will store a circularstring:

CREATE VARIABLE arc ST_CircularString;

Execute the following statement to create a circularstring and store it in the arc variable:

SET arc = NEW ST_CircularString( 'CircularString( -1 0, -0.707107 0.707107, 0 1 )' );

Execute the following statement to temporarily set the relative tolerance to 1% using the st_geometry_interpolation option.

SET TEMPORARY OPTION st_geometry_interpolation = 'relative-tolerance-percent=1';

Setting relative tolerance to 1% is optional, but makes the effects of interpolation more visible for the purposes of this example. For more information about relative tolerance and how to set it, see st_geometry_interpolation option.

Open the Spatial Viewer (in Interactive SQL, click Tools » Spatial Viewer) and execute the following query to view the circularstring:

SELECT arc
  UNION ALL SELECT arc.ST_CurveToLine()
  UNION ALL SELECT arc.ST_CurveToLine().ST_PointN( row_num )
  FROM RowGenerator WHERE row_num <= arc.ST_CurveToLine().ST_NumPoints();

Notice how the arc is broken into a sequence of linestring. Since relative tolerance was set to 1%, each line segment shows up as a line that bows in from the true arc. The maximum distance between the interpolated line string and the true arc is 1% of the radius of the arc.