3 ms·
I was wondering the same thing, but after staring at it a bit I think the problem is that one of them is doing math on the values from every row and the other i
by dec0dedab0de 5y ago
I was wondering the same thing, but after staring at it a bit I think the problem is that one of them is doing math on the values from every row and the other is doing the math once.
created_at + INTERVAL '90 DAY' < now() says that for every row take the created_at column, add 90 days to it, and then see if it is less than now()
created_at < now() - INTERVAL '90 DAY' says take now() subtract 90 days, and then see which rows are less than the result.
Atleast, thats my guess. I rarely do any db stuff directly.
- qwertox 5y agoIs "overflow" a term used to express "computed for every row"? I can see where the optimization would come from, when comparing `created_at` with a fixed value `now() - INTERVAL...` (assuming PostgreSQL is smart enough to evaluate it only once and reuse it for all the index comparisons), but the word "overflow" throws me out of the lane.