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Subject: Re: Counting unique items
From: Jan Lehnardt <jan@apache.org>
In-Reply-To: <2f84d03e0911211309w58359625na39a3af812200fa@mail.gmail.com>
Date: Sun, 22 Nov 2009 03:00:23 +0100
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References: <2f84d03e0911211309w58359625na39a3af812200fa@mail.gmail.com>
To: user@couchdb.apache.org


On 21 Nov 2009, at 22:09, Guy Moulton wrote:

> Hello,
>=20
> I'm trying to get a count of the number of unique items in a database.
> Documents look like this:
>=20
> Item: Item_A, User: Dave
> Item: Item_A, User: John
> Item: Item_A, User: Jane
> Item: Item_B, User: John
> Item: Item_B, User: Anne
>=20
> In the above example, I'd like to know that there are 2 items.  So
> far, I have a map/reduce that produces one view row for each kind of
> item (similar to the example on the wiki) :
>=20
> key: "Item_A", value:"Null"
> key: "Item_B", value:"Null"
>=20
> So the number I need is the number of rows in the view.
>=20
> According to the wiki, if I pass limit=3D0, it should give me the
> meta-data, but this doesn't seem to work on views that have a reduce
> function.  I don't want to count rows in the client as there could
> potentially be a very large number.
>=20
> Any ideas would be very much appreciated.

Hi Guy,

this might help you: =
http://books.couchdb.org/relax/reference/views-for-sql-jockeys#Get%20Uniqu=
e%20Values%20(SELECT%20DISTINCT%20field%20FROM%20table)

Cheers
Jan
--