I would recommend Kafka instead of Cassandra for your particular problem 
personally.

From: Jason Tang <ares.t...@gmail.com<mailto:ares.t...@gmail.com>>
Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" 
<user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Date: Wednesday, January 16, 2013 5:56 PM
To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" 
<user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Subject: Cassandra Consistency problem with NTP

Hi

I am using Cassandra in a message bus solution, the major responsibility of 
cassandra is recording the incoming requests for later consumming.

One strategy is First in First out (FIFO), so I need to get the stored request 
in reversed order.

I use NTP to synchronize the system time for the nodes in the cluster. (4 
nodes).

But the local time of each node are still have some inaccuracy, around 40 ms.

The consistency level is write all and read one, and replicate factor is 3.

But here is the problem:
A request come to node One at local time PM 10:00:01.000
B request come to node Two at local time PM 10:00:00.980

The correct order is A --> B
But the timestamp is B --> A

So is there any way for Cassandra to keep the correct order for read operation? 
(e.g. logical timestamp ?)

Or Cassandra strong depence on time synchronization solution?

BRs
//Tang




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