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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10885) Support visibility expressions on Deletes
Date Tue, 01 Apr 2014 08:04:14 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13956211#comment-13956211
] 

Andrew Purtell commented on HBASE-10885:
----------------------------------------

How we handle deletes in the AccessController is to only allow the delete if it has covering
permission. By that I mean CF ACLs and any ACLs in cells that would be covered by the tombstone
not already covered by a tombstone must grant the subject access. If any do not, the delete
is denied. We run an internal RegionScanner to enumerate the cells that would be affected
by the operation. 

One way to do this for the VisibilityController is we could similarly run an internal RegionScanner
with the parameters of the submitted Delete op, filter cells by effective visibility, and
issue deletes scoped only to those cells visible to the subject. This would be easier than
trying to hook compaction scanners and evaluating visibility expression tags there, because
we will have the effective label set for the user in the RPC context, not at compaction time.


> 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
>             Fix For: 0.99.0, 0.98.2
>
>
> 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 if they are visible to
the user issuing the delete or not. 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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