Andrew Lazarus <andrew@xxxxxxxxxxxx> writes: > Because I know the 25 closest are going to be fairly close in each > coordinate, I did try a multicolumn index on the last 6 columns and > used a +/- 0.1 or 0.2 tolerance on each. (The 25 best are very probably inside > that hypercube on the distribution of data in question.) > This hypercube tended to have 10-20K records, and took at least 4 > seconds to retrieve. I was a little surprised by how long that took. > So I'm wondering if my data representation is off the wall. A multicolumn btree index isn't going to be helpful at all. Jeff's idea of using six single-column indexes with the above query might work, though. regards, tom lane
