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Subject: Re: wild card on query
From: aaron morton <aaron@thelastpickle.com>
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Date: Fri, 17 Aug 2012 10:29:17 +1200
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To: user@cassandra.apache.org

> I want to retrieve all the photos from all the users of certain =
project. My sql like query will be "select projectid * photos from =
Users". How can i run this kind of row key predicate while executing =
query on cassandra?
You cannot / should not do that using the data model you have. (i.e. you =
could do it with a secondary index, but in this case you probably should =
not).

Try to de-normalise your data.=20

Say a CF called ProjectPhotos

* row key is the project_id
* column name is <timestamp:user_id>
* column value is image_url or JSON data about the image.=20

You would then slice some columns from one row in the  ProjectPhotos CF.=20=


You then need to know what images a user has uploaded, with say the =
UserPhotos CF.=20

* row key is user_id
* column name is timestamp
* column value is image_url or JSON data about the image.=20

I did a twitter sample app at http://wdcnz.com a couple of weeks ago =
that shows denormalising data  =
https://github.com/amorton/wdcnz-2012-site and =
http://www.slideshare.net/aaronmorton/hellow-world-cassandra

Hope that helps.=20

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 17/08/2012, at 12:39 AM, Swathi Vikas <swat.vikas@yahoo.com> wrote:

> Hi,
>=20
> I am trying to run query on cassandra cluster with predicate on row =
key.
>=20
> I have column family called "Users" and rows with row key like =
"projectid_userid_photos". Each user within a project can have rows like =
projectid_userid_blog, projectid_userid_status and so on.=20
>=20
> I want to retrieve all the photos from all the users of certain =
project. My sql like query will be "select projectid * photos from =
Users". How can i run this kind of row key predicate while executing =
query on cassandra?
>=20
> Any sugesstion will help.=20
>=20
> Thank you,
> swat.vikas
>>>=20
>>>=20
>>=20
>>=20
>>=20
>=20
>=20
>=20