Marcus,
Denormalization implies duplication. See this excellent article on the
subject:
http://highscalability.com/how-i-learned-stop-worrying-and-love-using-lot-disk-space-scale
In your case, you could keep the "role:" family that contains the row keys
to all roles (a user has) as a column key and value (or the value could be
the description) and if you have to know who has a particular role, have a
new family in Role named "user:" that would map the other way.
Same thing with category.
J-D
On Tue, Jul 22, 2008 at 9:33 AM, Marcus Herou <[EMAIL PROTECTED]>
wrote:
> Hi.
>
> What is the best practice in hbase when it comes to creating "mapping"
> tables between objects?
>
> Let's say you want to create two tables named "User" and "Role" where the
> user can be in many roles.
>
> User->Role
>
> I guess you could create some specially, proprietary cells like
> role:someuid
> which contains the ref to the Role table but this seems a little strange.
>
> Another quite normal example (for me at lesast) is to tag various content.
>
> Eg:
> BlogEntry<-BlogEntryCategory->Category
>
> where in a rdbms the BlogEntryCategory would just contain two cols
> blogEntryId and categoryId.
>
> Howto model that with column families ?
>
> Right now I'm creating Serializers which can serialize arrays back and
> forth
>
> Eg StringArraySerializer
> public byte[] serialize(Object object) throws IOException
> {
> String[] a = (String[])object;
> StringBuilder sb = new StringBuilder();
> for (int i = 0; i < a.length; i++)
> {
> sb.append(a[i]);
> if(i < (a.length - 1))
> {
> sb.append(this.delimiter);
> }
> }
> return sb.toString().getBytes("UTF-8");
> }
>
> public Object deserialize(byte[] bytes) throws IOException
> {
> String str = new String(bytes, "UTF-8");
> StringTokenizer st = new StringTokenizer(str, delimiter);
>
> List<String> list = new ArrayList();
> while(st.hasMoreTokens())
> {
> String token = st.nextToken();
> list.add(token);
> }
> return list.toArray(new String[list.size()]);
> }
>
>
> and then store the byte[] in hbase. Ugly....
>
> Please guide my sorry ass.
>
> Kindly
>
> //Marcus
>
>
>
>
> --
> Marcus Herou CTO and co-founder Tailsweep AB
> +46702561312
> [EMAIL PROTECTED]
> http://www.tailsweep.com/
> http://blogg.tailsweep.com/
>
