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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10885) Support visibility expressions on Deletes
Date Thu, 01 May 2014 03:18:15 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13986319#comment-13986319
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ramkrishna.s.vasudevan commented on HBASE-10885:
------------------------------------------------

In the current case only one gets applied.  So need to track the vis expression based on ts.
One more thing to note here is 
bq.For deleteFamily case all cells with ts <=103 are candidates for delete
Here because deleteFamily with ts = 103 satisfies the condition I think from that cell onwards
all the cells less than 103 should also be covered because it is deleteFamily.  If it is deleteFamilyVersion
then we need to check for exact match only.  But here I think once we find the cell with matching
visibility expression the ones below that also should get deleted.
Which means if a deleteFamily says ts = 103 and assume in this case the ts =101 only matches
the vis expression then from 101 on wards all cells less than 101 should be masked.

> Support visibility expressions on Deletes
> -----------------------------------------
>
>                 Key: HBASE-10885
>                 URL: https://issues.apache.org/jira/browse/HBASE-10885
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.98.1
>            Reporter: Andrew Purtell
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Blocker
>             Fix For: 0.99.0, 0.98.3
>
>         Attachments: HBASE-10885_1.patch, HBASE-10885_2.patch
>
>
> Accumulo can specify visibility expressions for delete markers. During compaction the
cells covered by the tombstone are determined in part by matching the visibility expression.
This is useful for the use case of data set coalescing, where entries from multiple data sets
carrying different labels are combined into one common large table. Later, a subset of entries
can be conveniently removed using visibility expressions.
> Currently doing the same in HBase would only be possible with a custom coprocessor. Otherwise,
a Delete will affect all cells covered by the tombstone regardless of any visibility expression
scoping. This is correct behavior in that no data spill is possible, but certainly could be
surprising, and is only meant to be transitional. We decided not to support visibility expressions
on Deletes to control the complexity of the initial implementation.



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