But wouldn't name + UUID be considered volatile? That was the crux of my questions.
On Fri, Mar 12, 2010 at 1:07 PM, Brandon Williams <dri...@gmail.com> wrote: > On Thu, Mar 11, 2010 at 12:54 AM, Peter Chang <pete...@gmail.com> wrote: > >> I'm wondering about good strategies for picking keys that I want to be >> lexically sorted in a super column family. For example, my data looks like >> this: >> >> [user1_uuid][connections][some_key_for_user2] = "" >> [user1_uuid][connections][some_key_for_user3] = "" >> >> I was thinking that I wanted some_key_for_user2 to be sorted by a user's >> name. So I was thinking I set the subcolumn compareWith to UTF8Type or >> BytesType and construct a key >> >> [user's lastname + user's firstname + user's uuid] >> >> This would result in sorted subcolumn and user list. That's fine. But I >> wonder what would happen if, say, a user changes their last name. Happens >> rarely but I imagine people getting married and modifying their name. Now >> the sort is no longer correct. There seems to be some bad consequences to >> creating keys based on data that can change. >> >> So what is the general (elegant, easy to maintain) strategy here? Always >> sort in your server-side code and don't bother trying to have the data >> sorted? >> > > Having row keys based on something potentially volatile is something I > would avoid since that determines which machine the row belongs to and > moving data between machines isn't a cheap operation. > > What you'll probably want to do is make the key something unique (like a > uuid), store the user's name as a column on the row (thus making it easy to > update) and maintain a secondary index to get the named-based sorting you > want. If you're expecting a few million users, maintaining the index in a > special row will work fine (eg, the row name is "NAMEINDEX" and the columns > are the name+uuid similar to what you described.) If you have billions of > users, you'll need to get a bit fancier (partition based on letter of the > last name, for example.) > > -Brandon >
