Hi everyone,
I'm trying to use cassandra in order to store a "timeline", but with values
that must be unique (replaced). (So not really a timeline, but didn't find a
better word for it)
Let's me give you an example :
- An user have a list of friends
- Friends can change their nickname, status, profile picture, etc...
at the beginning the CF will look like that for user1:
lte = latest-timestamp-entry, which is the timestamp of the entry (-1 -2 -3
means that the timestamp are older)
user1 row : | lte |
lte -1 | lte -2 | lte -3
| lte -4 |
values : | user2-name-change | user3-pic-change
| user4-status-change | user2-pic-change | user2-status-change |
If for example, user2 changes it's picture, the row should look like that :
user1 row : | lte |
lte -1 | lte -2 | lte -3
| lte -4 |
values : | user2-pic-change |
user2-name-change | user3-pic-change | user4-status-change |
user2-status-change |
notice that user2-pic-change in the first representation (lte -3) has "moved"
to the (lte) on the second representation.
That way when user1 connects again, It can retrieve only informations that
occurred between the last time he connected.
e.g. : if the user1's last connexion date it between "lte -2" and "lte -3",
then he will only be notified that :
- user2 has changed his picture
- user2 has changed his name
- user3 has changed his picture
I would not keep the old data since the "timeline" is saved locally on the
client, and not on the server.
I really would like not to search for each column in order to find the
"user2-pic-change", that can be long especially if the user has many friends.
Is there a simple way to do that with cassandra, or I am bound to create
another CF, with column title holding the action e.g. "user2-pic-change" and
for value the timestamp when it appears ?
Thanks,
Morgan.
