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Date: Fri, 10 Dec 2010 09:08:25 -0500
From: Jean-Pierre Fiset <jp@fiset.ca>
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To: user@couchdb.apache.org
Subject: Suppressing duplicate documents from a view query
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This question relates to CouchDb 1.0.1.

I have been reading as much as I can about CouchDb and started implementing an application. I
seem to remember that there is a request flag that can be passed to a view query to eliminate
document duplicates. However, I do not recall which one it is. A quick review of the wiki did
not shed any light.

Currently, I am removing duplicates by using a list function. I have documented the details of
the list function here:
http://www.bitsbythepound.com/remove-document-duplicates-from-couchdb-view-query-using-a-list-function-366.html

In short, this is the list function:

function(head, req) {
    send('{"total_rows":'+head.total_rows
        +',"offset":'+head.offset+',"rows":[');
    var ids = {}
        ,row
        ,first = true
        ;
    while(row = getRow()) {
        if( !ids[row.id] ) {
            if( first ) {
                first = false;
            } else {
                send( ',' );
            };
            send( toJSON(row) );
            ids[row.id] = 1;
        };
    };
    send(']}');
}

Questions:
1. Is there a much simpler way to achieve this?
2. If the list function is the way to solve the problem, can someone comment on the likelihood
that this function will sustain the scaling up of the database?

Thanks,

JP