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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-7755) Experiment with LAB in BlockEndcoding
Date Mon, 04 Feb 2013 05:52:12 GMT
Lars Hofhansl created HBASE-7755:

             Summary: Experiment with LAB in BlockEndcoding
                 Key: HBASE-7755
                 URL: https://issues.apache.org/jira/browse/HBASE-7755
             Project: HBase
          Issue Type: Bug
            Reporter: Lars Hofhansl

I was looking at and profiling the BlockEncoding code to figure out how to make it faster.
One issue that jumped out was we call ByteBuffer.allocate(...) for each single KV.
As an experiment I tried using the MemStoreLAB code to allocate those buffers.

Here are some preliminary numbers, all scanning 10m rows (all in cache):
* no encoding: 5.2s
* FAST_DIFF without patch: 7.3s
* FAST_DIFF with patch and small LAB: 4.1s
* FAST_DIFF with patch and large LAB: 11s

So this is very sensitive to the right sizing of the LAB.

Need to do a bit more testing, but it seems that there is a chance to actually make scanning
with block encoding faster than without!

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