Postgres ORDER BY speed

[Anon]

Hello,

I'm having a problem with the speed fo the ORDER BY in postgres. I'm doing this on a table of about 600,000 rows. My explain shows it's using the index (index scan backwards).

Is there something I'm missing ?

EXPLAIN SELECT uid FROM site_profiles ORDER BY profiles_last_login;

Index Scan using idx_profiles_last_login on site_profiles (cost=0.00..438256.71 rows=545785 width=16)

Thanks, Keith

[[deleted]]

Do you have enough sort-buffer memmory assigned to postgres?

[Anon]

well i have tried raising sort_mem from 128000 to 5120000 and saw no difference.

I have enable_sort = false, does this make a difference ? (setting it to true didnt change a thing however)