Batch Mutation In Cassandra?

Question

I want to update multiple rows in 2 CF's. I don't care about the order they get updated ? But is it guaranteed that if one gets succeeded then eventually others will get too if some C* node fails in between ?

Hector BatchMutation class use batch update or atomic batch update as these are two separate things.

Answer 1

You should use an atomic batch in CQL3. This guarantees that either the entire batch succeeds or the entire batch fails. An example from the CQL3 docs:

BEGIN BATCH
  INSERT INTO users (userid, password, name) VALUES ('user2', 'ch@ngem3b', 'second user');
  UPDATE users SET password = 'ps22dhds' WHERE userid = 'user3';
  INSERT INTO users (userid, password) VALUES ('user4', 'ch@ngem3c');
  DELETE name FROM users WHERE userid = 'user1';
APPLY BATCH;

The Hector BatchMutation class uses the Thrift operation batch_mutate. This is weaker than atomic_batch_mutate, which is the Thrift equivalent of the above. batch_mutate is only atomic for updates on the same key (can be different CFs though), whereas atomic_batch_mutate is atomic on all updates. I don't think Hector has implemented atomic_batch_mutate so you will need to move to CQL3 and a CQL3-capable driver e.g. DataStax's java driver.