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https://issues.apache.org/jira/browse/HBASE-10885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13980520#comment-13980520
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Andrew Purtell edited comment on HBASE-10885 at 4/25/14 12:00 AM:
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On sorting of terminals or not, a discussion that Ram, Anoop, and I had
included this topic and it seems reasonable to change the serialization. I
think we should start by splitting out the custom visibility tag serialization
in VisibilityController to a separate file. We could put magic bytes in front
and test for those, falling back to an expensive comparison of we don't find
the magic, otherwise use one optimized for sorted representation. While we are
at it we could use protobuf for the new serialization and so the magic preamble
would be 'PBUF' I suppose.
was (Author: apurtell):
On sorting of terminals or not, a discussion that Ram, Anoop, and I included
this topic and it seems reasonable to change the serialization. I think we
should start by splitting out the custom visibility tag serialization in
VisibilityController to a separate file. We could put magic bytes in front and
test for those, falling back to an expensive comparison of we don't find the
magic, otherwise use one optimized for sorted representation. While we are at
it we could use protobuf for the new serialization and so the magic preamble
would be 'PBUF' I suppose.
> 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: Critical
> 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 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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