Thank you Jeff. There are 7 million rows satisfying fk_id_client = 20045. There is an index on fk_id_client, now I added a composite (fk_id_client, id) index but that did not help.
I see the point of what you are saying, but still don't understand how these two situations (*asc* vs. *desc*) are not symmetrical. I mean, there /is/ an ascending index on *JOB_MEMORY.id*, so why does it matter which end I am picking the data from? The thing is, even when I force Postgres to use the ascending index on *id*, it's still orders of magnitude slower than the *desc* version (even when that one goes through the index backwards). -- View this message in context: http://www.postgresql-archive.org/Huge-difference-between-ASC-and-DESC-ordering-tp5947712p5947737.html Sent from the PostgreSQL - performance mailing list archive at Nabble.com.
