On Thu, 4 Oct 2001, Jason Earl wrote: > My guess is that compared to the task of sorting > millions of names the fact that you have to lowercase > them first is not going to be a particular burden. No > matter what you do you are going to get a table scan > (unless you qualify your select with a where clause). > > You can, however, create an index like: > > create index MyTable_lower_idx on MyTable > (lower(name)); > > It won't help with your particular query, but it > certainly would help for queries like:
Current sources do (and I think older sources may) consider such an index to replace the sort step. On a test table with 100000 strings, explain shows an index scan for the lower(<col>) ordering and a seq scan/sort for <col> ordering. At this point there's actually a performance gain for the lower() index scan. ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
