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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-2251) PE defaults to 1k rows - uncommon use case, and easy to hit benchmarks
Date Tue, 23 Feb 2010 16:32:27 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837298#action_12837298
] 

Todd Lipcon commented on HBASE-2251:
------------------------------------

I would argue a zipf law distribution probably reflects reality. Constant sized rows are probably
friendlier on gc / fragmentation / etc, no? There should at least be *some* rows that are
bigger than the hfile block size, too.

> PE defaults to 1k rows - uncommon use case, and easy to hit benchmarks
> ----------------------------------------------------------------------
>
>                 Key: HBASE-2251
>                 URL: https://issues.apache.org/jira/browse/HBASE-2251
>             Project: Hadoop HBase
>          Issue Type: Bug
>            Reporter: ryan rawson
>             Fix For: 0.20.4, 0.21.0
>
>
> The PerformanceEvaluation uses 1k rows, which I would argue is uncommon, and also provides
an easy to hit performance goal.  Most of the harder performance issues happens at the low
and high side of cell size.  In our own application, our key sizes range from 4 bytes to maybe
100 bytes.  Very rarely 1000 bytes.  If we have large values, they are VERY large, like multiple
k sizes.
> Recently a change went into HBase that ran well with PE because the overhead of 1k rows
is very low in memory, but under small rows, the expected performance would be hit much more.
 This is because the per-value overhead (eg: node objects of the skip list/memstore) is amortized
more with 1k values. 
> We should make this a tunable setting, and have a low default.  I would argue for a 10-30
byte default.

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