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https://issues.apache.org/jira/browse/KUDU-1767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15706375#comment-15706375
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Mike Percy commented on KUDU-1767:
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Pulling in some comments from KUDU-1761.
>From [~dralves]:
{quote}
You're suggesting that EO semantics should enforce write order but my point
was: how is the server supposed to know that the client requires order
enforcement versus just trying to do multiple writes at the same time?
There's a "happened before" relationship here that we're expecting to be
enforced and that I think should be enforced in the client, outside of EO
semantics.
{quote}
>From [~tlipcon]:
{quote}
I agree that the exactly-once stuff should have no bearing on request ordering;
it's only meant to provide idempotency, not any other cross-request guarantees,
and I think it would be a mistake to try to bend it into providing some kind of
serialization order (for the same reason David mentioned).
My vote is that we commit a change to the client API docs that makes this
behavior more clear – probably on the 'Flush' API and on the docs for the
different flush modes. It's a slightly surprising bit of semantics, so worth
noting, but I don't think it's worth prioritizing a fix at this point in time.
{quote}
> Reordering of client operations from the same KuduSession is possible
> ---------------------------------------------------------------------
>
> Key: KUDU-1767
> URL: https://issues.apache.org/jira/browse/KUDU-1767
> Project: Kudu
> Issue Type: Bug
> Components: client, tablet
> Affects Versions: 1.1.0
> Reporter: Mike Percy
> Priority: Critical
>
> It is possible for client operations written via the same KuduSession to be
> reordered on the server side in MANUAL_FLUSH and AUTO_BACKGROUND_FLUSH modes.
> This violates our desired consistency guarantees.
> This may occur because we allow concurrent flushes from the client for
> throughput reasons and there is nothing enforcing the well-ordering of lock
> acquisition from a single client session on the server side.
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