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: Re: Huge difference between ASC and DESC ordering
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