Gabriel Reid created PHOENIX-1578:
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Summary: 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
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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