SQL substring non greedy regex

Question

I have data like

http://www.linz.at/politik_verwaltung/32386.asp

stored in a text column. I thought a non-greedy extraction with

select substring(turl from '\..*?$') as ext from tdata

would give me .asp but instead it still ?greedely results in

 .linz.at/politik_verwaltung/32386.asp

How can I only match against the last occurence of dot .?
Using Postgresql 9.3

Answer 1

\.[^.]*$ matches . followed by any number of non-dot characters followed by end-of-string:

# select substring('http://www.linz.at/politik_verwaltung/32386.asp' 
  from '\.[^.]*$');
 substring 
-----------
 .asp
(1 row)

As for why the non-greedy quantifiers do not work here is that they still start matching as soon as possible while still trying to match as short as possible from there on.