[
https://issues.apache.org/jira/browse/ACCUMULO-803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13477087#comment-13477087
]
Adam Fuchs commented on ACCUMULO-803:
-------------------------------------
You could do both count up and count down logical time on many different groups
of keys in the same tablet with only persisting one timestamp. If the plugin
framework supports a one-up counter, a plugin can then subtract that from max
long or transform it otherwise as necessary for each timestamp group. This
would maintain the monotonicity property of logical time on any of the groups
of entries at the cost of introducing sparcity (which doesn't really matter).
> Add Reverse Logical Time as a Time Type
> ---------------------------------------
>
> Key: ACCUMULO-803
> URL: https://issues.apache.org/jira/browse/ACCUMULO-803
> Project: Accumulo
> Issue Type: Improvement
> Components: tserver
> Affects Versions: 1.4.2
> Reporter: Drew Farris
> Assignee: Drew Farris
> Priority: Minor
> Attachments: ACCUMULO-803.patch
>
>
> In a context where we are doing aggregation/combination of multiple values
> for a given key it may be useful to iterate over the values associated with
> that key in the order in which the mutations were applied (FIFO), instead of
> the FILO order that seems to occur when using {{TimeType.LOGICAL}}.
> I encountered when implemeting a checkAndPut operation that would ensure that
> the previous value was expected before putting a new value. In this case, if
> the previous value was not as expected, the mutation would be ignored.
> Perhaps it is useful in a general case?
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
