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https://issues.apache.org/jira/browse/ZOOKEEPER-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13042837#comment-13042837
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Marshall McMullen commented on ZOOKEEPER-965:
---------------------------------------------

I'm now finishing up the other suggestion Benjamin had about using a boolean 
placeholder for a checkop instead of having a real Stat structure in there. 
This is also simpler than I was thinking so I should have this done shortly. 
Just testing it out now to ensure no regressions. And actually, as it turns out 
I don't even need a boolean at all -- just a placeholder. B/c if the check 
failed, then we put a Error txn/response in the result array on the server side 
not a check response. Anyhow, should have this done in the next 30 minutes.

> Need a multi-update command to allow multiple znodes to be updated safely
> -------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-965
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-965
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.3.3
>            Reporter: Ted Dunning
>            Assignee: Ted Dunning
>             Fix For: 3.4.0
>
>         Attachments: ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, ZOOKEEPER-965.patch, 
> ZOOKEEPER-965.patch
>
>
> The basic idea is to have a single method called "multi" that will accept a 
> list of create, delete, update or check objects each of which has a desired 
> version or file state in the case of create.  If all of the version and 
> existence constraints can be satisfied, then all updates will be done 
> atomically.
> Two API styles have been suggested.  One has a list as above and the other 
> style has a "Transaction" that allows builder-like methods to build a set of 
> updates and a commit method to finalize the transaction.  This can trivially 
> be reduced to the first kind of API so the list based API style should be 
> considered the primitive and the builder style should be implemented as 
> syntactic sugar.
> The total size of all the data in all updates and creates in a single 
> transaction should be limited to 1MB.
> Implementation-wise this capability can be done using standard ZK internals.  
> The changes include:
> - update to ZK clients to all the new call
> - additional wire level request
> - on the server, in the code that converts transactions to idempotent form, 
> the code should be slightly extended to convert a list of operations to 
> idempotent form.
> - on the client, a down-rev server that rejects the multi-update should be 
> detected gracefully and an informative exception should be thrown.
> To facilitate shared development, I have established a github repository at 
> https://github.com/tdunning/zookeeper  and am happy to extend committer 
> status to anyone who agrees to donate their code back to Apache.  The final 
> patch will be attached to this bug as normal.

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