There will be many times when you will need to generate a less detailed and lighter version of a vector dataset, as you may not need very detailed features for several reasons. Think about a case where you are going to publish the dataset to a website and performance is a concern, or maybe you need to deploy the dataset to a colleague who does not need too much detail because they are using it for a large-area map. In all these cases, GIS tools include implementations of simplification algorithms that reduce unwanted details from a given dataset. Basically, these algorithms reduce the vertex numbers comprised in a certain tolerance, which is expressed in units measuring distance.
For this purpose, PostGIS provides you with the ST_Simplify and ST_SimplifyPreserveTopology functions. In many cases, they are the right solutions for simplification tasks, but...
