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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ACCUMULO-2837) Scanning empty table can be optimized
Date Mon, 06 Apr 2015 03:13:12 GMT

     [ https://issues.apache.org/jira/browse/ACCUMULO-2837?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Josh Elser updated ACCUMULO-2837:
---------------------------------
    Labels: performance  (was: )

> Scanning empty table can be optimized
> -------------------------------------
>
>                 Key: ACCUMULO-2837
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2837
>             Project: Accumulo
>          Issue Type: Bug
>    Affects Versions: 1.6.0
>            Reporter: Keith Turner
>            Assignee: Keith Turner
>            Priority: Trivial
>              Labels: performance
>             Fix For: 1.6.3, 1.8.0, 1.7.1
>
>
> I wrote an application that repeatedly scanned random rows in an empty table at one point.
 It did not know the table was empty.  I was jstacking the tserver and repeatedly saw stack
traces in a few places in the code. 
>  * the audit canScan method
>  * DefaultConfiguration.get
>  * Kept seeing Password token ungziping the password??????
> After fixing all of these issues (except for system token) I ran a simple test I saw
times go from ~1.7s to ~1.3s for a simple test I wrote to recreate this issue.
> I am not sure how much of an impact the gziping the password has.  I was just sampling
the stack traces manually.  I seems like I saw the password token gzip stack traces less frequently,
but I did catch it multiple jstack calls.



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