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From "Jonathan Gray (JIRA)" <j...@apache.org>
Subject [jira] Created: (HBASE-1252) Make atomic increment perform a binary increment
Date Tue, 10 Mar 2009 19:04:50 GMT
Make atomic increment perform a binary increment
------------------------------------------------

                 Key: HBASE-1252
                 URL: https://issues.apache.org/jira/browse/HBASE-1252
             Project: Hadoop HBase
          Issue Type: Improvement
    Affects Versions: 0.19.0
            Reporter: Jonathan Gray
            Assignee: Jonathan Gray
            Priority: Minor
             Fix For: 0.19.1, 0.20.0


A few issues related to recently committed HBASE-803

- The HTable api still takes an integer amount rather than long, mismatching HRI.
- Binary increments are 10 times faster for small amounts than going Bytes.toLong, += amount,
Bytes.toBytes.  Twice as fast for large amounts (binary incrementor just loops a bunch of
single increments, though there is plenty of room for optimizations in my current implementation)
- Using a binary increment means we don't have to worry about the size of the value.  If someone
wants a 16 byte value they can have it, just have to initialize as such.  If no existing value
exists, will default to long/8 bytes.  Only odd behavior will be what happens when you are
at the max value, currently will just stay at all 11111 binary.  Could actually grow the byte[]
but then we can't do things in place. I'm okay with leaving it like that, not exactly sure
what the current implementation would do, throw an exception or wrap?

- Using binary incrementing, we can directly manipulate values in the memcache rather than
sending updates with the same timestamp.  I think we should hold off on doing this until HBASE-1234
goes in.  We'll then have to deal directly with hlog.  (this issue is not going to address
this)

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