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From Jukka Zitting <jukka.zitt...@gmail.com>
Subject Re: Running background operation on a single node in a Oak cluster
Date Wed, 20 Nov 2013 16:46:55 GMT
Hi,

On Wed, Nov 20, 2013 at 5:33 AM, Chetan Mehrotra
<chetan.mehrotra@gmail.com> wrote:
> Would it make sense to make use of this feature to run the Async Index
> Update only on one node?. It would also help in avoiding the conflict
> while concurrently updating the index related data in cluster.

The async index update is designed so that it should work correctly
even when run concurrently on multiple cluster nodes. It uses
optimistic locking to prevent conflicting updates.

Thus I'd rather not limit the async index update to just one node, and
instead leave it running throughout the cluster. The update contains
code that's designed to automatically detect conflicting updates and
suppress any warnings about them. Do you still see conflicts being
logged?

The only case I know where having concurrent updaters is troublesome
is when a large import is being indexed, as that would cause lots of
duplicate and unnecessary work on all cluster nodes. Perhaps we should
add an extra flag in the index that the updater can use to signal to
other cluster nodes that the latest set of changes is already being
processed.

BR,

Jukka Zitting

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