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From "Alexander Shorin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COUCHDB-1868) Using multiple keys, the _all_docs built-in view acts differently then a user defined view
Date Mon, 12 Aug 2013 15:50:48 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-1868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13736969#comment-13736969
] 

Alexander Shorin commented on COUCHDB-1868:
-------------------------------------------

I believe the reason of such behaviour is simple: user's views can have duplicated keys, _all_docs
- couldn't. So _all_docs behaviour for keys isn't applicable to user views.

Why _all_docs returns error information on missed key? Probably, to help make stateless applications
when after request you don't need to know payload to process response data. Anyway, it's useful
behaviour, since you may show user, which requested documents ids are missed without need
to handle his query somewhere in middleware.
                
> Using multiple keys, the _all_docs built-in view acts differently then a user defined
view
> ------------------------------------------------------------------------------------------
>
>                 Key: COUCHDB-1868
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1868
>             Project: CouchDB
>          Issue Type: Bug
>          Components: View Server Support
>            Reporter: Filippo Fadda
>
> When you query a view using multiple keys, the _all_docs built-in view acts differently
then a user defined view:
> 1) in the first case CouchDB returns "not_found" for every not found key;
> 2) querying a user defined view produces, instead, an empty array.
> In the first case you obtain error="not_found" for every key, when you query a user defined
view you simply don't get any rows, just the total rows for the view.
> See: http://pastebin.com/D7NExJrd
> Now, regarding 'keys' the documentation says something like: "Used to retrieve just the
view rows matching that set of keys. Rows are returned in the order of the specified keys."
> In a normal case, CouchDB should return just a row for each matched key, but it will
really help, having an option to return a row for every key, even there if not found, because
it's more easy, cycle through results.
> Let's suppose the application I'm doing gets the last 30 blog posts, displaying for each
one, information that are stored into related documents. The application will query, using
as keys the posts' identifiers, other views to get, for example, if a post has been starred
from the current logged-in user, etc.
> If a view always returns a number of rows equals to the number of keys, the application
can cycle from 0 to 29 and display all the related information for a post.

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