follower/following in cassandra

Question

We are designing a twitter like follower/following in Cassandra, and found something similar

from here https://www.slideshare.net/jaykumarpatel/cassandra-at-ebay-13920376/13-Data_Model_simplified_13

so I think ItemLike is a table? itemid1=>(userid1, userid2...) is a row in the table? what do you think is the create table of this ItemLike table?

Answer 1

Yes, ItemLike is a table

Schema of the ItemLike table will be Like :

CREATE TABLE itemlike(
    itemid bigint,
    userid bigint,
    timeuuid timeuuid,
    PRIMARY KEY(itemid, userid)
); 

The picture of the slide is the internal structure of the above table.

Let's insert some data :

 itemid | userid | timeuuid
--------+--------+--------------------------------------
      2 |    100 | f172e3c0-67a6-11e7-8e08-371a840aa4bb
      2 |    103 | eaf31240-67a6-11e7-8e08-371a840aa4bb
      1 |    100 | d92f7e90-67a6-11e7-8e08-371a840aa4bb

Internally cassandra will store the data like below :

--------------------------------------------------------------------------------------|
|    |             100:timeuuid              |            103:timeuuid                | 
|    +---------------------------------------+----------------------------------------|
|2   | f172e3c0-67a6-11e7-8e08-371a840aa4bb  |  eaf31240-67a6-11e7-8e08-371a840aa4bb  |
--------------------------------------------------------------------------------------|

---------------------------------------------|
|    |             100:timeuuid              |
|    +---------------------------------------|
|1   | d92f7e90-67a6-11e7-8e08-371a840aa4bb  |
---------------------------------------------|