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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 17:10:28 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837317#action_12837317
] 

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

bq. Then I can write a Hudson plugin that fails a build if performance is out of line beyond
some threshold. What do you think?

Even in the absence of automatically failing builds, Hudson has a facility to easily generate
a graph with build # on the x axis and arbitrary data on the y axis - you just have to generate
the data in .properties format for each build. At a web company I worked for in the past,
we had graphs for # db queries, # cache queries, page load time, etc, for each of the important
pages on the site. It was very easy to spot bad commits, but also easy to see if we were inching
up slowly over time (even more insidious than a bad commit imo).

> 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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