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Posted to dev@omid.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2017/08/06 10:52:03 UTC
[jira] [Commented] (OMID-73) Add Checkpoints and visibility levels
[ https://issues.apache.org/jira/browse/OMID-73?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16115761#comment-16115761 ]
ASF GitHub Bot commented on OMID-73:
------------------------------------
Github user ohadshacham closed the pull request at:
https://github.com/apache/incubator-omid/pull/12
> Add Checkpoints and visibility levels
> -------------------------------------
>
> Key: OMID-73
> URL: https://issues.apache.org/jira/browse/OMID-73
> Project: Apache Omid
> Issue Type: New Feature
> Reporter: Ohad Shacham
> Assignee: Ohad Shacham
> Attachments: OMID-73.v1.patch
>
>
> A checkpoint is a point in a transaction where every write occurs after the checkpoint may not be visible by the transaction.
> The visibility is defined by the following visibility levels:
> SNAPSHOT - returns the last written key by the transaction, in case one exists, otherwise, returns the key from the transaction snapshot.
> SNAPSHOT_EXCLUDE_CURRENT - returns the last written key by the transaction that was written before the last checkpoint, in case one exists, otherwise, returns the key from the transaction snapshot.
> SNAPSHOT_ALL - returns all the versions written by the transaction including the one in the transaction snapshot.
> This feature is needed for Phoenix both for upsert operations and for correct rollback of the secondary index on transaction abort.
> Explanations for this feature can be seen in [TEPHRA-96].
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