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HBase, mail # dev - Limited cross row transactions


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Re: Limited cross row transactions
Lars George 2012-01-17, 21:31
Sounds sweet Lars!

On Jan 17, 2012, at 4:27 PM, lars hofhansl wrote:

> I just committed HBASE-5203 (together with HBASE-3584 this implements atomic row operations).
> Although a relatively small patch it lays the groundwork for heterogeneous operations in a single WALEdit.
>
> The interesting part is that even though the code enforced the atomic operation to be a for single row, this is not required.
> It is enough if all involved KVs reside in the same region.
>
> I am not saying that we should add any high level concept to HBase (such as the EntityGroups of Megastore).
>
> But, with a slight addition to the API (allowing a grouping of multiple row operations) client applications have all the building blocks to do limited cross row atomic operations.
> The client application would be responsible for either correctly pre-splitting the table, or a custom balancer has to be provided.
>
> The operation would fail if the regionserver determines that it would need data from multiple region servers.
>
> I think this needs at least minimal support from HBase and cannot (efficiently or without adding more moving parts) by a client API only.
>
>
> Comments? Is this worth pursuing? If so, I'll file a jira and provide a patch.
>
> Thanks.
>
>
> -- Lars
>