[postgis-users] Grouping by geom with count?

[James David Smith]

Hi all,

A bit of advice please. I have a table of about 250,000 linestring.
They represent peoples routes on roads around London. I would like to
use them in QGIS now to show the most used roads by making them a
darker colour. So to do this I feel I need to do some sort of grouping
of the geometries with a count column too - so that I can use that
count column to define the darkness of the line on my map.

How could I go about doing this please?

The problem I can see in my head is that let's say I have one
linestring which goes from A to B. Then another linestring that goes
from A to B to C. When I group the geometries, these won't group as
they aren't the same. However I would want the result to be that
linestring A to B is given a value of 2 and the bit of the line from B
to C would be given a value of 1.

I think I'm perhaps overcomplicating this...

Thanks

James