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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Naive question about orphan rows
Date Wed, 26 Feb 2014 13:55:35 GMT
It is probably ok to have redundant songs in playlists, cassandra is about
denormalization.

Dealing with this issue is going to be hard since the only way to dwal with
this would be scanning through the firsr cf and procing counts then using
that information to delete in the second table. However that information
can change rapidly and then will fall out of sink fast.

The only ways yo handle this are

1) never delete songs
2) store copies of songs ib playlist

On Friday, February 21, 2014, Green, John M (HP Education) <
john.green@hp.com> wrote:
> I'm very much a newbie so this may be a silly question but ...
>
>
>
> I have a situation similar to the music service example (
http://www.datastax.com/documentation/cql/3.1/cql/ddl/ddl_music_service_c.html)
of songs and playlists.  However, in my case, the "songs" would be
considered orphans that should be deleted when no "playlists" refer to
them.  Relational databases have mechanisms to manage this relationship so
that a "song" could be deleted as soon as the last "playlist" referencing
it is deleted.    While I do NOT need to manage this as an atomic
transaction, I'm wondering what is the best way to delete orphaned rows
(i.e., "songs" not referenced by any "playlists")  using Cassandra.
>
>
>
> I guess an alternative approach would be to store "songs" directly in the
"playlists" but this could lead to many redundant copies of the same "song"
which is something I'm hoping to avoid.  I'm my case the "playlists" could
have thousands of entries and the "songs" might be blobs of 10s of
Mbytes.    Maybe I'm just having a hard time abandoning my relational roots?
>
>
>
> John

-- 
Sorry this was sent from mobile. Will do less grammar and spell check than
usual.

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