| From: | David Kerr <dmk(at)mr-paradox(dot)net> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: killing processes |
| Date: | 2009-07-21 17:47:04 |
| Message-ID: | 20090721174704.GD32936@mr-paradox.net |
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| Lists: | pgsql-general |
On Tue, Jul 21, 2009 at 01:13:18PM -0400, Tom Lane wrote:
- David Kerr <dmk(at)mr-paradox(dot)net> writes:
- I tried it on a table with 899991 random values. It took frickin'
- forever, but seemed to be willing to respond to cancels anywhere
- along the line. I'm not sure why you're seeing differently.
Hehe, yeah. For me I let it run 10 min and hit ^C so maybe i just
hit it at a bad place.
- (The reason it takes forever is that numeric is a variable-width
- type, and access into a varwidth array is O(n), so the sorting
- step you've got here is O(n^2). It might help to use unnest()
- instead of this handmade version of it ...)
unnest() is 8.4 only, right?
I'm actually probably just going to install R and use the median
function from that. (I was hoping to avoid installing all of R)
Or maybe i'll try my hand at a perl one and see if that gives
ok performance.
Thanks!
Dave
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