Hi,
we did something similar. We did utilize some cassandra code though and
wrote a custom commitlog reader that outputs our data into a readable form.
You can look here:
http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/1.1.9/org/apache/cassandra/db/commitlog/CommitLogReplayer.java
This code is used to replay commitlogs when starting up cassandra. It
has the ability to deserialize and transform the data into what you'll need.
-- artur
On 18/03/14 19:32, Han,Meng wrote:
Hi Jonathan,
Thank you for the timely reply. I am doing this experiment on a
continuous basis. To be more specific, I will issue a large amount of
read and write operations to a particular key in a short time
interval. I'd like to know the order that write operations happens at
each replica. TImestamps definitely help to determine order, but the
WRITETIME and SStable2Json both looks me only return the timestamps
when that key was updated the moment the WRITETIME/SStable2Json is
issued. It looks like a one time thing to me. Or put in another way,
if I want to get the write time for all write operations in that short
invertal to determine a total order for write on that replia I have to
constantly issue WRITETIME to this replica? Correct me if I am wrong
here.
Light me up pleeeeeeeeeease!
On Tue, 18 Mar 2014 15:05:07 -0400, Jonathan Lacefield wrote:
Hello,
Is this a one time investigative item or are you looking to set
something up to do this continuously? Don't recommend trying to read
the commit log.
You can always use the WRITETIME function in CQL or look within
SSTables via the SStable2Json utility to see write times for
particular versions of partitions.
Jonathan
Jonathan Lacefield
Solutions Architect, DataStax
(404) 822 3487
<http://www.linkedin.com/in/jlacefield>
<http://www.datastax.com/what-we-offer/products-services/training/virtual-training>
On Tue, Mar 18, 2014 at 2:25 PM, Han,Meng <meng...@ufl.edu
<mailto:meng...@ufl.edu>> wrote:
Hi Cassandra hackers!
I have a question regarding extracting useful information from
commit log.
Since its a binary log, how should I extract information such as
timestamp, values from it? Does anyone know any binary log reader
that I can use directly to read commit log?
If there is no such reader, could someone give me some advice hwo
I can wrote such a reader?
Particularly, I want to know the order that write operations
happens at each replica(cassandra server node) along with their
timestamps, Does anyone know other methods how I can get this
information without instrumenting Cassandra code?
Any help is appreciated!
Cheers,
Meng
