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https://issues.apache.org/jira/browse/HBASE-10354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13888069#comment-13888069
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Nicolas Liochon commented on HBASE-10354:
-----------------------------------------
{code}
/**
* Eventual consistent reads might return values that may not see
* the most recent updates. Write transactions are always performed
* in strong consistency model in HBase. In eventual consistency,
* the order of observed transactions is always in the same sequence
* that the transactions were written.
* Reads will be seeing a previous version of the database.
*/
{code}
I don't understand this part: with 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?
For these 3 versions, what are the scenarios that cannot happen with our
consistency model?
> 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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