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From "Arthur Zubarev" <Arthur.Zuba...@Aol.com>
Subject Re: Creating namespace and column family from multiple nodes concurrently
Date Thu, 23 May 2013 20:15:54 GMT
so where the multiple nodes are? I am just puzzled 

From: Emalayan Vairavanathan 
Sent: Thursday, May 23, 2013 3:43 PM
To: Arthur Zubarev ; user@cassandra.apache.org 
Subject: Re: Creating namespace and column family from multiple nodes concurrently

"Would each device/machine have its own keyspace?"

No. All the machines are going to run the exactly same CQL commands and going to create the
same namespace and column families.

Thank you
Emalayan


--------------------------------------------------------------------------------
From: Arthur Zubarev <Arthur.Zubarev@Aol.com>
To: Emalayan Vairavanathan <svemalayan@yahoo.com>; user@cassandra.apache.org 
Sent: Thursday, 23 May 2013 12:20 PM
Subject: Re: Creating namespace and column family from multiple nodes concurrently


Would each device/machine have its own keyspace?

Basically, your client needs to take care of a successful creation of the schema and any other
verifications and it is going to be time consuming. 

From: Emalayan Vairavanathan 
Sent: Thursday, May 23, 2013 3:07 PM
To: user@cassandra.apache.org 
Subject: Re: Creating namespace and column family from multiple nodes concurrently

Hi Arthur and Farraz,


Thank you for getting back to me.


I am trying to avoid sync among concurrent instances and this is why I am preferring Option
- 2. Further in my application, I have reasonable window between the application initialization
phase and the application runtime.  So as long as Cassandra can safely handle concurrent creation
I should be fine.


Do you have any idea how Cassandra is going to handle concurrent namespace and column family
creation (Here all the instances are going to create the same namespace and column families
concurrently)? 
        - Does Cassandra take much time to agree on a final schema (In case if Cassandra is
using some sort of exponential back off algorithms to handle schema conflicts) ? 
        - Or is it going to result schema conflicts which needs manual intervention ?
        - Or will this result in race conditions ?
        - Or some other issues e.g: memory/ cpu /network bottlenecks ?  


Thank you
Emalayan


--------------------------------------------------------------------------------
From: Arthur Zubarev <arthur.zubarev@aol.com>
To: user@cassandra.apache.org; svemalayan@yahoo.com 
Sent: Wednesday, 22 May 2013 8:07 PM
Subject: Re: Creating namespace and column family from multiple nodes concurrently


I am assuming here you want to sync all the 100s of nodes once the application is airborne.
I suspect this would flood the network and even potentially affect the machine itself memory-wise.
How are you going to maintain the nodes (compaction+repair)? 


Regards,

Arthur




-----Original Message-----
From: Emalayan Vairavanathan <svemalayan@yahoo.com>
To: user <user@cassandra.apache.org>
Sent: Wed, May 22, 2013 8:31 pm
Subject: Creating namespace and column family from multiple nodes concurrently


Hi all,

I am implementing a distributed application which runs on 100s of machines concurrently. This
application is going to use Cassandra as underlaying storage.

The application creates the schema (name space and column families) during initialization
phase.  It seems I have two options to create the schema.


Option - 1 : Using a single node for schema creation.
        Option - 2: Having all the nodes (> 100) to run the same schema creation logic
(First, nodes will check whether the schema is already available and then try to create the
schema if it is not available already).  

To keep the initialization phase simple, I prefer to go for Option - 2. However I am not sure
how Cassandra is going to behave if multiple nodes try to create the same schema (namespace
and column families) concurrently. It would be nice if someone can tell me about the implications
of Option - 2 with Cassandra version 1.2.2.


Please let me know if you have question.


Thank you
VE





 







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