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https://issues.apache.org/jira/browse/PHOENIX-1578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14279997#comment-14279997
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James Taylor commented on PHOENIX-1578:
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Thinking about this a bit more, [~gabriel.reid], I don't think we need it in
the 3.x branch. It's kind of enabling feature for other things, so since
further development won't be done on 3.x, it's probably not worth it. Time
would be better spent on 4.x work.
> Support explicit storage of null values
> ---------------------------------------
>
> Key: PHOENIX-1578
> URL: https://issues.apache.org/jira/browse/PHOENIX-1578
> Project: Phoenix
> Issue Type: New Feature
> Reporter: Gabriel Reid
> Assignee: Gabriel Reid
> Fix For: 5.0.0, 4.3
>
> Attachments: PHOENIX-1578-docs.patch, PHOENIX-1578.2.patch,
> PHOENIX-1578.patch
>
>
> Null values are currently represented implicitly by a lack of a KeyValue for
> a given field. This is implemented by using an HBase delete to remove cells
> when a given field is set to null via an upsert statement.
> However, this method of setting values to null causes all previous versions
> of the given field to be removed on the next major compaction, which prevents
> doing flashback queries for the given field.
> One workaround for this is to enable KEEP_DELETED_CELLS on the underlying
> HBase table -- however, this means that SQL deletes (i.e. DELETE FROM TABLE)
> will never actually remove the data.
> This ticket is to propose a flag (defined at table level) which specifies
> that null values to be explicitly stored in HBase. This flag should not
> change the behavior of a SQL {{DELETE}} statement, i.e. a SQL {{DELETE}} will
> still cause a record to be permanently deleted (including historical data).
> The use of this flag in combination with KEEP_DELETED_CELLS=false and
> VERSIONS=unlimited will allow Phoenix to provide true row-level versioning.
> Additional background in this mail thread: http://s.apache.org/kwz
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