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From kannan chandrasekaran <>
Subject Few questions regarding cassandra deployment on windows
Date Tue, 07 Sep 2010 22:42:32 GMT
Hi All,

We are currently considering Cassandra for our application. 

* a single-node cluster.
* windows '08
* 64-bit jvm  

For the sake of brevity let,
Cassandra service =  a single node cassandra server running as an embedded 
service inside a JVM

My use cases: 
1) Start with a schema ( keyspace and set of column families under it) in a 
cassandra service
2) Need to be able to replicate the same schema structure (add new 
keyspace/columnfamilies with different names ofcourse).
3) Because of some existing limitations in my application, I need to be able to 
write to the keyspace/column-families from a cassandra service and read the 
written changes from a different cassandra service. Both the write and the read 
"cassandra-services" are sharing the same Data directory. I understand that the 
application has to take care of any naming collisions. 

Couple Questions related to the above mentioned usecases:
1) I want to spawn a new JVM and launch Cassandra as an embedded service 
programatically instead of using the startup.bat. I would like to know if that 
is possible and any pointers in that direction would be really helpful. ( 
2) I understand that there are provisions for live schema changes in 0.7 ( thank 
you guys !!!), but since I cant use a beta version in production, I am 
restricted to 0.6 for now. Is it possible to to support use-case 2 in 0.6.5 ? 
More specifically, I am planning to make runtime changes to the storage.conf xml 
file followed by a cassandra service restart
3) Can I switch the data directory at run-time ?  (use-case 3). In order to not 
disrupt read while the writes are in progress, I am thinking something like, 
copy the existing data-dir into a new location; write to a new data directory; 
once the write is complete; switch pointers and restart the cassandra service to 
read from the new directory to pick up the updated changes

Any help is greatly appreciated.


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