Hi Shweta,
shweta.agrawal wrote:
Hi,
Is transaction type facility available in Accumulo?
I have read about transaction in accumulo which says " Accumulo
guarantees these ACID properties for a single mutation (a set of changes
for a single row) but does not provide support for atomic updates across
multiple rows"
This might be easier to reason about if you consider the Java API.
When you make a Mutation, all updates in that mutation will be applied
or rejected.
Mutation m = new Mutation("row".getBytes());
m.put("cf", "cq1", "value1");
m.put("cf", "cq2", "value2");
batchwriter.put(m);
batchwriter.close();
In this case, Accumulo will either have 2 K/V pairs in "row" ("cf:cq1"
=> "value1", "cf:cq2" => "value2") or no K/V pairs in "row".
In my case:
If one thread is updating the fields of a document then this document
should be locked so that other thread cannot modify that document.
I am trying to achieve this by a query through conditional mutation. I
am checking whether the particular entry exist or not then updating. But
the problem is I am doing this through 150 threads. If one thread finds
and updating particular entry then other thread should not get it.
So is this the case in conditional write?
We are achieving same thing through mongoDB by find and modify feature.
If one thread get particular document to update from conditional write
then other thread should get that particular document.
I'm not 100% sure how best to go about this. Maybe you could use a
special column in the row to do the exclusion?
write cf:lock <my_client1>
_update columns_
delete cf:lock <my_client1>
Keith probably has a better suggestion :)
Please provide your inputs
Thanks
Shweta
