I agree with this approach. I do something similar using _sum:
emit([doc.country_name, toDay(doc.timestamp)], 1);
The toDay() method is basically a floor of the day value. Since I don't
store ts in UTC (Because of an idiotic error some years back) I also do
a tz offset to correct the day value in my toDay() method.
Using reduce is by far the fastest method for this. I don't see any
issue with getting this to scale.
Overall, I think I rather prefer the method Keith shows, as it would
depend on the values returned in the date object versus other possibly
inaccurate means using math.
Wendall
On 04/15/2013 07:18 AM, Keith Gable wrote:
Output keys like so:
[2010, 7, 10, "Australia"]
Reduce function would be _count.
startkey=[year,month,day,null]
endkey=[year,month,day,{}]
---
Keith Gable
A+, Network+, and Storage+ Certified Professional
Apple Certified Technical Coordinator
Mobile Application Developer / Web Developer
On Sun, Apr 14, 2013 at 8:37 PM, Andrey Kuprianov <
[email protected]> wrote:
Hi guys,
Just for the sake of a debate. Here's the question. There are transactions.
Among all other attributes there's timestamp (when transaction was made; in
seconds) and a country name (from where the transaction was made). So, for
instance,
{
. . . .
"timestamp": 1332806400
"country_name": "Australia",
. . . .
}
Question is: how does one get unique / distinct country names in between
dates? For example, give me all country names in between 10-Jul-2010 and
21-Jan-2013.
My solution was to write a custom reduce function and set
reduce_limit=false, so that i can enumerate all countries without hitting
the overflow exception. It works great! However, such solutions are frowned
upon by everyone around. Has anyone a better idea on how to tackle this
efficiently?
Andrey
