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https://issues.apache.org/jira/browse/HBASE-10354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13888256#comment-13888256
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Enis Soztutar commented on HBASE-10354:
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bq. +1 on above... TIMELINE or STALE or STALE_ALLOWED?
I'll rename to TIMELINE.
bq. Do we have to have a pb and java enum? Maybe for the client API but does it
have show up on the server? Can it just be pb enum on server.
We need two enums for the client side. We cannot expose the PB to the client.
In server side, Consistency is only accessed through a Get or Scan object. So
in places where we can expose PB get and scan objects, we can equally go with
PB version of consistency.
bq. This has to be public?
I can see Result.setExists() which is exposed. The PB version of Result does
not have the stale parameter, because we were setting it from the client side
because we know the RPC went to a replica. But I think we should carry it over
the PB Result as well. We might still need setStale() for PB -> POJO conversion
though.
bq. This going into a branch?
Yes, these will go into the branch.
bq. what we doing, for 3 versions v1, v2, v3, a reader can see something like
v3, v2, v1: by going first on the primary, then on a secondary with a less
recent version, then on another secondary with the oldest version. What we
guarantee is that at a point all the clients will see v3, but until this point
is reached, everything can happen?
Yes indeed. I'll reword that javadoc. The guarantee is on the server side,
rather than on the client side. If you are sticking to a server you will always
see transactions in order, but if you are jumping from server to server (like
in the failover RPC implementation) then there are no guarantees within
different secondary replicas. We can implement further guarantees if we do
pipelined writes and ordered requests to replicas, but not in the first cut.
> Add an API for defining consistency per request
> -----------------------------------------------
>
> Key: HBASE-10354
> URL: https://issues.apache.org/jira/browse/HBASE-10354
> Project: HBase
> Issue Type: Sub-task
> Components: Client
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Fix For: 0.99.0
>
> Attachments: hbase-10354_v1.patch
>
>
> We should add an API to be able to define the expected consistency level per
> operation. This API should also allow to check whether the results coming
> from a query (get or scan) is stale or not. The defaults should reflect the
> current semantics.
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