qgis - How to extract POINT from a [LINE|MULTILINE]STRING

I'd like to create a vectorLayer in QGIS to display all the points that form a LINESTRING or a MULTILINESTRING stored in a PostGIS DB.

I think that I need to transform all points of LINESTRING (or MULTILINESTRING) to POINT.

First Question:

Is there any PostGIS function to do that?

Second Question:

If I want to exclude duplicate points from the result POINT table, how can I do that?

Answer

To get point in order and link to orginal geometry use

SELECT (ST_DumpPoints(the_geom)).path as path, id, (ST_DumpPoints(the_geom)).geom FROM linestrings)

and remove dublicates from http://wiki.postgresql.org/wiki/Deleting_duplicates

remember that you need to have one unique id for dublicate removing, if you dont have one you need to create it