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PostGIS

Introduction
Points
Linestrings
Polygons
Summary

Instruction

Great! One more exercise coming your way.

Exercise

Usually, a point signifies a place where a line bends. Help Mark find the routes with fewest bends so he can maintain a steady pace!

Find the average length among bicycle routes with fewer than 30 points. Provide the result in meters.

Stuck? Here's a hint!

To count the average, use the following construction:

AVG(ST_Length(ST_Transform(..., ...)))

Remember that the SRID for San Francisco with meters as the unit of measure is 26910.

To pick only routes with fewer than 30 points, write a proper WHERE condition using the ST_Npoints() function.