[jira] [Created] (OMID-73) Add Checkpoints and visibility levels

["Ohad Shacham (JIRA)" <ji...@apache.org>]

Ohad Shacham created OMID-73:
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             Summary: 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


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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