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From Robert Samuel Newson <rnew...@apache.org>
Subject Re: question about "complex" range queries
Date Wed, 02 Apr 2014 22:45:46 GMT
A view is a single dimension index, ordered by the full key in accordance with the rules enumerated
here: https://wiki.apache.org/couchdb/View_collation#Collation_Specification

For example;

9 sorts after false
999 sorts after 9
"foo" sorts after 999
["foo"] sorts after "foo"
["foo", "bar"] sorts after ["foo"]

B.

On 2 Apr 2014, at 23:29, rian.maloney@yahoo.com wrote:

> I have a quick question related to this. What exactly is sorted? My test cases indicated
the key AND the entire value is sorted as if it was one big string. 
> 
> Thanks
> Rian
> 
> On Apr 2, 2014, at 2:31 AM, Nick North <north.n@gmail.com> wrote:
> 
>> It doesn't work quite like this. There is a single order across all
>> possible keys, including both simple and complex keys, as described
>> here<https://wiki.apache.org/couchdb/View_collation>.
>> In the case of keys that are lists, the two lists are compared element by
>> element and the sort order is the sort order of the first unequal elements.
>> 
>> In your example, if a key has its first element between a1 and a2 (and a1
>> and a2 are different), then the second element will not be inspected at
>> all, so it does not matter whether it is between b1 and b2 or not. In fact
>> the second element will only be inspected if the first element is either a1
>> or a2.
>> 
>> This is usually the behaviour we want. For example, dates are often
>> represented as lists of [year, month, day]. Then you can pull out all the
>> documents in a date range by specifying start date and end date as startkey
>> and endkey. For example, if these are [2012, 4, 5] and [2014, 8, 3]
>> respectively, we want to include [2013, 3, 6] in the output even though its
>> second element does not lie between the second elements of the keys.
>> 
>> Nick
>> 
>> 
>> On 2 April 2014 03:56, Schroiff, Klaus <KlausS@fast.au.fujitsu.com> wrote:
>> 
>>> Hi,
>>> 
>>> Let's assume that I have the following view function:
>>> 
>>> function(doc) { emit([a, b], whatever) } }
>>> 
>>> In the query I'm running something like
>>> startkey=[a1, b1] & endkey=[a2,b2]
>>> Thus there're TWO explicit ranges here - a1->a2 and b1->b2.
>>> 
>>> What is the expected result ?
>>> 
>>> My understanding:
>>> The query is executed in two phases
>>> In the first phase, the index is filtered for qualifying results where the
>>> first key ranges from a1 to a2
>>> In the second phase, these filtered results are filtered once more
>>> according to the range of the second emitted key from b1 to b2.
>>> Thus essentially an "AND" operation.
>>> The filtering is performed using lexicographical rules.
>>> 
>>> Is that correct ? The doc about complex keys is a bit slim.
>>> 
>>> Thanks
>>> 
>>> Klaus
>>> 
>>> 


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