In the last exciting episode, ch.pingel@xxxxxx (Christoph Pingel) wrote: > I'm new to PostgreSQL, and it has been a pleasure so far. > > There's just one thing I'm trying to do and I didn't find any hints in > the manual: I want to index just a part of a string in a column. > > The situation: I have roughly 300.000 rows, and in the column we're > looking at, most of the entries have less than 200 chars. However, > there are some (very few) that have more than 3000 chars, and > postmaster relplies that this is too many for the index (b-tree). > > So I would like to say 'index only the first 200 chars of the column', > which will result in a full index of 99.9 % of my entries. I did this > in MySQL, but I didn't find it in the pg manual. > > How do I proceed? You might look at using a functional index: <http://www.postgresql.org/docs/7.3/interactive/indexes-functional.html> You'd therefore create a "first_200_chars()" function, and then create an index using that function. -- wm(X,Y):-write(X),write('@'),write(Y). wm('cbbrowne','gmail.com'). http://cbbrowne.com/info/postgresql.html Signs of a Klingon Programmer #10: "You cannot really appreciate Dilbert unless you've read it in the original Klingon." ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
