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Subject: Re: data model question : finding out the n most recent changes items
From: aaron morton <aaron@thelastpickle.com>
In-Reply-To: 
 <CAJn6JDS4HBpSs=R1D=KDpc-1=gpWcPVC7jo0STFDoG2e+=u-yQ@mail.gmail.com>
Date: Thu, 11 Jul 2013 19:00:55 +1200
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Message-Id: <26B2EA04-2477-4B85-A4A8-76B76B37237C@thelastpickle.com>
References: 
 <CAJn6JDS4HBpSs=R1D=KDpc-1=gpWcPVC7jo0STFDoG2e+=u-yQ@mail.gmail.com>
To: user@cassandra.apache.org

What you described this sounds like the most appropriate:

CREATE TABLE user_file (
	user_id uuid,
	modified_date timestamp,
	file_id timeuuid,
	PRIMARY KEY(user_id, modified_date)
);

If you normally need more information about  the file then either store =
that as additional fields or pack the data using something like JSON or =
Protobuf.=20

> my return list may still not accurate because a single directory could =
have lot of modification changes. I basically end up pulling out series =
of modification timestamp for the same directory.
Not sure I understand the problem.=20

Cheers


-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 10/07/2013, at 6:51 PM, Jimmy Lin <y2klyf+work@gmail.com> wrote:

> I have an application that need to find out the n most recent modified =
files for a given user id. I started out few tables but still couldn't =
get what i want, I hope someone get point to some right direction...
>=20
> See my tables below.
>=20
> #1 won't work, because file_id's timeuuid contains creation time, not =
the modification time.
>=20
> #2 won't work, because i can't order by a non primary key =
column(modified_date)
> #3,#4 although i can now get  a time series of modification time of =
each file belongs to a user, my return list may still not accurate =
because a single directory could have lot of modification changes. I =
basically end up pulling out series of modification timestamp for the =
same directory.
>=20
> Any suggestion?
>=20
> Thanks
>=20
>=20
>=20
> #1
>=20
> CREATE TABLE user_file (
>=20
> user_id uuid,
>=20
> file_id timeuuid,
>=20
> PRIMARY KEY(user_id, file_id)
>=20
> );
>=20
>=20
>=20
> #2
>=20
> CREATE TABLE user_file (
>=20
> user_id uuid,
>=20
> file_id timeuuid,
>=20
> modified_date timestamp,
>=20
> PRIMARY KEY(user_id, file_id)
>=20
> );
>=20
>=20
>=20
> #3
>=20
> CREATE TABLE user_file (
>=20
> user_id uuid,
>=20
> file_id timeuuid,
>=20
> modified_date timestamp,
>=20
> PRIMARY KEY(user_id, file_id, modified_date)
>=20
> );
>=20
>=20
>=20
> #4
>=20
> CREATE TABLE user_file (
>=20
> user_id uuid,
>=20
> modified_date timestamp,
>=20
> file_id timeuuid,
>=20
> PRIMARY KEY(user_id, modified_date, file_id)
>=20
> );
>=20
>=20
>=20
>=20
>=20