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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-9553) Pad HFile blocks to a fixed size before placing them into the blockcache
Date Tue, 17 Sep 2013 00:18:52 GMT
Lars Hofhansl created HBASE-9553:
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             Summary: Pad HFile blocks to a fixed size before placing them into the blockcache
                 Key: HBASE-9553
                 URL: https://issues.apache.org/jira/browse/HBASE-9553
             Project: HBase
          Issue Type: Bug
            Reporter: Lars Hofhansl


In order to make it easy on the garbage collector and to avoid full compaction phases we should
make sure that all (or at least a large percentage) of the HFile blocks as cached in the block
cache are exactly the same size.

Currently an HFile block is typically slightly larger than the declared block size, as the
block will accommodate that last KV on the block. The padding would be a ColumnFamily option.
In many cases 100 bytes would probably be a good value to make all blocks exactly the same
size (but of course it depends on the max size of the KVs).

This does not have to be perfect. The more blocks evicted and replaced in the block cache
are of the exact same size the easier it should be on the GC.

Thoughts?


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