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Date: Tue, 16 Oct 2012 14:39:54 -0400
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 <CABvT1DEbwrG00e=nuxPCsrtGA-52=igzKop9ZXUyZsapjAXTgA@mail.gmail.com>
Subject: Re: (Dynamically) excluding documents from a view query
From: Robert Newson <rnewson@apache.org>
To: dev@couchdb.apache.org
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I think that would require you to read the entire view every time, though.

On 16 October 2012 10:53, boazc <bcitrin@gmail.com> wrote:
> Thanks Robert.
>
> It crossed my mind that I can use List function and expect say include-ke=
ys
> and exclude-keys query parameters thus filter out the undesired documents=
.
> 1. Do you think the performance of such function will be reasonable?
> 2. Can I still support pagination through a List function?
>
> Cheers.
>
> On Tue, Oct 16, 2012 at 3:30 PM, Robert Newson-2 [via CouchDB Development=
] <
> ml-node+s1959287n7581300h65@n2.nabble.com> wrote:
>
>> I can't speak about ElasticSearch, but the CouchDB-Lucene query would
>> certainly reflect the current state of your database (i.e, no "delay")
>> when you query.
>>
>> As for the original question, I don't think you can achieve it
>> directly with CouchDB views. If you emit each tag of a document as a
>> key, and null for value (e.g, emit("a",null)), then you could make two
>> concurrent queries for ?key=3Da and ?key=3Db, and read each, row by row,
>> filtering out as appropriate. It's not trivial.
>>
>> B.
>>
>> On 16 October 2012 05:50, boazc <[hidden email]<http://user/SendEmail.jt=
p?type=3Dnode&node=3D7581300&i=3D0>>
>> wrote:
>>
>> > Hello,
>> >
>> > My documents contain tags which have a corresponding view.
>> > I want to retrieve all documents that contain a certain tag, but don't
>> > contain another one.
>> > (Note that I don't know about the possible tags in advance).
>> >
>> > Example:
>> > id: doc1, tags: [a, b]
>> > id: doc2, tags: [b, c]
>> > id: doc3, tags: [a, c]
>> > If I want all docs with tag=3Da but not tag=3Db I expect to get only d=
oc3.
>> >
>> > Is there a way to achieve this on CouchDB side?
>> > Needless to say I cannot do it on the client side as I cannot benefit
>> from
>> > pagination and anyway might receive an extreme set of documents I need
>> to
>> > work on.
>> >
>> > I know I can turn to some search engines e.g. ElasticSearch or
>> > CouchDB-Lucene, but other than introducing a new component to the syst=
em
>> it
>> > also means an inherent delay between the "real" data and the indexed
>> data
>> > which in my domain is unacceptable.
>> >
>> > Thanks!!
>> >
>> >
>> >
>> > --
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