Optimistic Concurrency using versioning about cassandra-driver-mapping HOT 4 CLOSED

Sorry, I am not clear of your question.
There is no race condition or blocking for version column on read.
Version column is read the same way as any other columns.
The only difference is on write:
if what you write has ver different from what is in DB the write will not succeed.
I hope this helps

from cassandra-driver-mapping.

I mean during write operation does't driver first need to read what's the
current version in db to compare it with the version being written so that
err could be thrown if the version being written is old?
If we're reading for comparison before finally writing then how that read is concurrency issue free?
On Mar 28, 2015 4:26 AM, "Eugene" [email protected] wrote:

Sorry, I am not clear of your question.
There is no race condition or blocking on version column on read.
Version column is read the same way as any other columns.
The only difference is on write:
if what you write has ver different from what is in DB the write will not
succeed.
I hope this helps

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from cassandra-driver-mapping.

There is no read operation before write.
please read this link to understand the concept
http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_ltwt_transaction_c.html

Mapper uses Lightweight transactions feature provided by Cassandra.
Update statement contains IF condition to compare version (IF version=object.version)
Cassandra guaranties that update happens only when condition is met.

Lightweight transactions comes with performance cost.
This is Cassandra limitation but not my mapper or datastax driver.

from cassandra-driver-mapping.

Ok so it being ensured by LWT, got it thanks!

from cassandra-driver-mapping.