[ 
https://issues.apache.org/jira/browse/OMID-73?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16098266#comment-16098266
 ] 

ASF GitHub Bot commented on OMID-73:
------------------------------------

Github user ebortnik commented on a diff in the pull request:

    https://github.com/apache/incubator-omid/pull/12#discussion_r129018404
  
    --- Diff: 
transaction-client/src/main/java/org/apache/omid/transaction/AbstractTransaction.java
 ---
    @@ -37,14 +38,22 @@
      */
     public abstract class AbstractTransaction<T extends CellId> implements 
Transaction {
     
    +    enum VisibilityLevel {
    --- End diff --
    
    Please add some comments about visibility levels


> 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
>
> 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]. 



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

Reply via email to