I think this should do what I want
select trunc(distance * 10.)/10., count(*)
from doc_ads
group by 1 order by 1
Thanks, Joel
--
- for hire: mac osx device driver ninja, kernel extensions and usb d
What is the meaning of
group by 1 order by 2
e.g. what to the numbers 1 and 2 stand for?
What would change if I do the following?
group by 1 order by 1
On Apr 30, 2011, at 5:48 PM, Thomas Markus wrote:
> Hi,
>
> try something like this:
>
> select
>trunc(random(
Thank you Thomas!
Is there a way for the code below to determine the number of rows in the table
and use it?
Thanks, Joel
On Apr 30, 2011, at 5:48 PM, Thomas Markus wrote:
> Hi,
>
> try something like this:
>
> select
>trunc(random() * 10.)/10.
>, count(*)
> from
>generat
I have a column of 2 million float values from 0 to 1.
I would like to figure out how many values fit into buckets spaced by 0.10,
e.g. from 0 to 0.10, from 0.10 to 0.20, etc.
What is the best way to do this?
Thanks, Joel
Tom,
On Apr 26, 2011, at 5:00 PM, Tom Lane wrote:
> For another couple orders of magnitude, convert the sub-function to C code.
> (I don't think you need
> a whole data type, just a function that does the scalar product.)
That's a 30x speedup, from 12 minutes down to 38s. Thanks Tom!
On Apr 26, 2011, at 4:31 PM, Scott Marlowe wrote:
> It's a reasonable start. However, if you consistently using less than
> that in aggregate then lowering it is fine.
Is there a way to tell if I consistently use less than that in aggregate?
> What's your work_mem and max_connections set to?
I'm running pgsql on an m1.large EC2 instance with 7.5gb available memory.
The free command shows 7gb of free+cached. My understand from the docs is that
I should dedicate 1.75gb to shared_buffers (25%) and set effective_cache_size
to 7gb.
Is this correct? I'm running 64-bit Ubuntu 10.10, e.g
Folks,
I'm trying to optimize the following query that performs KL Divergence [1]. As
you can see the distance function operates on vectors of 150 floats.
The query takes 12 minutes to run on an idle (apart from pgsql) EC2 m1 large
instance with 2 million documents in the docs table. The CPU i
