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From Antony Blakey <antony.bla...@gmail.com>
Subject Re: The need for a key prefix view parameter
Date Fri, 01 May 2009 00:07:21 GMT

On 01/05/2009, at 12:49 AM, Wojciech Kaczmarek wrote:

> On Thu, Apr 30, 2009 at 16:56, Brian Candler <B.Candler@pobox.com>  
> wrote:
>> On Thu, Apr 30, 2009 at 02:23:17PM +0100, Brian Candler wrote:
>>> (5) Strangely, doc id keys in _all_docs appear to behave  
>>> differently;
>>> perhaps they are ASCII-compared rather than UCA compared. See  
>>> script 3
>>> below.
>>
>> And this has just had me tearing my hair out for the last half  
>> hour: a
>> search for
>>
>>    _all_docs?startkey="_design/"&endkey="_design/ZZZZ"
>>
>> did not match some of my documents, e.g. _design/c000. Now I  
>> realise that
>> almost certainly this is because Z comes before c in ASCII collation.
>>
>> Is this intentional behaviour? If so I will change the Wiki so it  
>> recommends
>>
>>    _all_docs?startkey="_design/"&endkey="_design/~"
>
> Isn't it better to use "\u9999" as the ending marker?


\u9999 isn't the final unicode collation point - firstly that's not  
the last value in a 16 bit space, secondly unicode isn't 16 bits, and  
finally, unicode collation is locale dependent.

I've previously argued that the only way to do this correctly is to  
allow a prefix search defined over all JSON values: http://mail-archives.apache.org/mod_mbox/couchdb-dev/200901.mbox/%3c67C42C78-4F52-409A-847B-F545F664D190@gmail.com%3e

Antony Blakey
--------------------------
CTO, Linkuistics Pty Ltd
Ph: 0438 840 787

Only two things are infinite, the universe and human stupidity, and  
I'm not sure about the former.
  -- Albert Einstein


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