James Taylor created HBASE-11803:
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Summary: Programming model for reverse scan is confusing
Key: HBASE-11803
URL: https://issues.apache.org/jira/browse/HBASE-11803
Project: HBase
Issue Type: Bug
Components: Client
Affects Versions: 0.98.1
Reporter: James Taylor
The reverse scan is a very nice feature in HBase. We leverage it in Apache
Phoenix 4.1 when possible and see a huge boost in performance over re-ordering
the result set ourselves.
However, the way in which you have to adjust the start/stop key is confusing.
Our use case is that we have a scan that needs to be done and we've calculated
an inclusive start row and an exclusive stop row. This is the way region
boundaries are which is convenient as they can easily be intersected against
the scan stop/start row. When we use a reverse scan, we are forced to switch
the start and stop row values of the scan *and* adjust the byte values from
inclusive to exclusive and from exclusive to inclusive. The former is not too
bad, as you can just add a zero byte, but the latter is problematic. You can
decrease the last byte by one, but you need to add an indeterminate 0xFF bytes
to ensure you're not including a row unintentionally.
IMHO, it would be much cleaner to just keep the start/stop row as is and just
set call the Scan.setReversed(true) method.
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