Breaking a Linestring into Segments

Like doing a sudoku, solving a “simple yet tricky” problem in spatial SQL can grab ones mind and hold it for a period. Someone on the PostGIS IRC channel was trying to “convert a linestring into a set of two-point segments”, using an external C++ program, and I thought: “hm, I’m sure that’s doable in SQL”.

And sure enough, it is, though the syntax for referencing out the parts of the dump objects makes it look a little ugly.