Select distinct count cloudant/couchdb

Question

I am starting a project using Cloudant. It\'s a simple system for logging, so I can track the usage of my apps.

My documents looks like this:

{
app:\'na

Answer 1

For what you need there is a feature on couldant/couchdb called design document. You can check their documentation for this feature for details or this guide: http://guide.couchdb.org/draft/design.html

Cloudant documentation: https://docs.cloudant.com/design_documents.html Design documents are similar views on the SQL world.

Regards,

Answer 2

We were able to do this in our project using the Cloudant Java API...

https://github.com/cloudant/java-cloudant

You should be able to get this sort of result by creating a view that has a map function like this...

function(doc) {
    emit([doc.app, doc.date, doc.owner], 1);
}

The reduce function should look like this:

function(keys, values, rereduce){
    if (rereduce){
        return sum(values);
    } else {
        return sum(values);
    }
}

Then we used the following query to get the data we wanted.

Database db = ....
db.view(viewName).startKey(startKeys).endKey(endKeys)
            .group(true).includeDocs(false).query(castClass)

We supplied the view name and some start and end keys (since we emitted a compound key and we needed to supply a filter) and then used the group method to get the data back as you need it.

Revised..

With this new emit key in the map function you should get results like this:

{[
{[app1, 2015,06,28, john@somewhere.net], 12}, <- john visited 12 times     on that day...
{[app1, 2015,06,29, john@somewhere.net], 10},
{[app1, 2015,06,28, ann@somewhere.net], 1}
]}

If you use good start and end keys, the amount of records you're querying will stay small and the number of records you get back is the unique visitors you are seeking. Note that in this scenario you are getting back a bit more than you want, but it does work.

Answer 3

You can do this using design documents, as Cesar mentioned. A concrete example would be to create a view where your map function emits the field on where you want to group on, such as:

function(doc) {
  emit(doc.email, 1);
}

Then, you select your desired reduce function (such as _count). When viewing this on Cloudant dashboard, make sure you select Reduce as part of the query options. When accessing the view via URL you need to pass the appropriate parameters (reduce=true&group=true).

The documentation on Views here is pretty thorough: https://docs.cloudant.com/creating_views.html