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From "Paul Davis" <paul.joseph.da...@gmail.com>
Subject Re: View with incremental counter
Date Tue, 18 Nov 2008 14:59:55 GMT
If this is easy and you see an implementation, I think it'd be a great
addition to force the sand boxing of individual functions.

That said, I don't know much about the JS internals so I'm not sure
how hard it would be to auto detect what might cause side effects
outside the function and what wouldn't. I've stuck largish objects
outside the function itself on the assumption that they'll only be
instantiated once as opposed to once per document.

I have absolutely no idea if that's even necessary though.

Paul

On Tue, Nov 18, 2008 at 9:51 AM, Benjamin Nortier <bjnortier@gmail.com> wrote:
> Should CouchDB not restrict defining state outside the map function?
> I.e. you should not be able to declare a counter outside the function?
>
> On Tue, Nov 18, 2008 at 1:42 PM, Jedediah Smith
> <jedediah@silencegreys.com> wrote:
>>
>> You can't maintain a state across calls to map functions in this way. Map
>> functions can be called in any order or in parallel, any number of times on
>> a particular document and in completely separate environments. They should
>> not have any side effects or depend on any outside state.
>>
>> You should read up on Google's MapReduce and maybe functional programming in
>> general in order to understand how CouchDB works.
>>
>> If you just want to number the results of your view, that can be easily done
>> by the calling code.
>>
>> Adam Groves wrote:
>>>
>>> Hi,
>>>
>>> I've got the following view:
>>>
>>> count = 0;
>>> function(doc) {
>>>  if(doc.type == "document") {
>>>    count = count + 1
>>>    emit(doc._id, count);
>>>  }
>>> }
>>>
>>> The idea is that I get a list of documents, each having a counter
>>> value which is incremental. I expected the count values to come out in
>>> order, but that isn't the case: my first few documents have values of
>>> 62, 61, 22, 19. I'm not quite sure what's going on here - any ideas
>>> how the order is being set here?
>>>
>>> Regards
>>>
>>> Adam Groves
>>>
>>
>
>
>
> --
> Benjamin Nortier
> e: bjnortier@gmail.com
> c: +44 (0)778 946 1959
> msn: bjnortier@mail.com
> gtalk: bjnortier@gmail.com
>

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