Comments inside..
2010/9/26 Lucas Nodine <lucasnod...@gmail.com>:
> I'm looking at a design where multiple clients will connect to Cassandra and
> get/mutate resources, possibly concurrently. After planning a bit, I ran
> into the following scenero for which I have not been able to research to
> find an answer sufficient for my needs. I have found where others have
> recommended Zookeeper for such tasks, but I want to determine if there is a
> simple solution before including another product in my design.
>
> Make the following assumption for all following situations:
> Assuming multiple clients where a client is someone accessing Cassandra
> using thrift. All reads and writes are performed using the QUORUM
> consistency level.
>
> Situation 1:
> Client A ("A") connects to Cassandra and requests a QUORUM consistency level
> get of an entire row. At or very shortly thereafter (before A's request
> completes), Client B ("B") connects to Cassandra and inserts (or mutates) a
> column (or multiple columns) within the row.
>
> Does A receive the new data saved by B or does A receive the data prior to
> B's save?
Shoud receive A stuff.
>
> Situaton 2:
> B connects and mutates multiple columns within a row. A requests some data
> therein while B is processing.
>
> Result?
Depends.. is it done in BatchMutate or not ?
>
> Situation 3:
> B mutates multiple columns within multiple rows. A requests some data
> therein while B is processing.
>
> Result?
See above..
>
> Justification: At certain points I want to essentially lock a resource (row)
> in cassandra for exclusive write access (think checkout a resource) by
> setting a flag value of a column within that row. I'm just considering race
> conditions.
>
You will need to use cages or something like that..
> Thanks,
>
> Lucas Nodine
Bye,
Norman
