# Segmenting Open Street Map Streets Using PostGIS.

This blog post gives an overview on how to segment streets in OSM data.

## Overview

A street in OSM data is a linestring. A Linestring represents a sequence of points and line segments connecting them. Segmenting is a process of dividing a segment into multiple segments.

## Need for Segmenting

Let us suppose there is a big street represented by a linestring. Let us suppose that we interested in a particular part of the street and not the whole street. In such cases we may have to segment the bigger street into small streets.

A figure explaining the above:

## Some PostGIS Functions

Before we start with segmentation, let us first try to understand some basic PostGIS functions which are used in segmentation process.

ST_Split function splits geometries and returns a collection of geometries. The code below illustrates an example