Update Where or Locking with ElasticSearch?

I have a document property in an ElasticSearch index called 'processing.'
It's a boolean value that records whether or not an external program is
running that is working with that document. I am running many external
processors, but documents cannot be processed by multiple programs at once.

Am I able to select a document that is not being processed and update the
'processing' property to TRUE without another processor sneaking in and
choosing the document? Is there an UPDATE WHERE type operation I can
perform that will return the _id of the document that was updated?

--

On Mon, 2012-11-26 at 21:49 -0800, Brian Jones wrote:

I have a document property in an ElasticSearch index called
'processing.' It's a boolean value that records whether or not an
external program is running that is working with that document. I am
running many external processors, but documents cannot be processed by
multiple programs at once.

Am I able to select a document that is not being processed and update
the 'processing' property to TRUE without another processor sneaking
in and choosing the document? Is there an UPDATE WHERE type operation
I can perform that will return the _id of the document that was
updated?

Yes you can - use the update api, pass the current version number and
leave retry_on_conflict set to zero:
http://www.elasticsearch.org/guide/reference/api/update.html

alternatively, you could just use the create and delete APIs. If you try
to create a document with a particular ID and it fails, then something
else has already created it. Once the job is done, delete the document.

clint

--