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Date: Fri, 22 May 2009 06:58:46 -0700 (PDT)
From: "Knut Anders Hatlen (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Updated: (DERBY-4233) Lower tablescan performance right
 after database creation in 10.5
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     [ https://issues.apache.org/jira/browse/DERBY-4233?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Knut Anders Hatlen updated DERBY-4233:
--------------------------------------

    Priority: Minor  (was: Major)

Lowering the priority since the problem appears to be very limited. The change that triggered the problem looks harmless, so it may be reasonable to suspect that external factors are more likely to be the real cause (for example an instability in the JVM's optimizer and the change just happens to make it pick the suboptimal choice more frequently in this particular situation).

> Lower tablescan performance right after database creation in 10.5
> -----------------------------------------------------------------
>
>                 Key: DERBY-4233
>                 URL: https://issues.apache.org/jira/browse/DERBY-4233
>             Project: Derby
>          Issue Type: Bug
>          Components: Performance, SQL
>    Affects Versions: 10.5.1.1
>         Environment: Solaris Express Community Edition snv_114 X86
> java version "1.6.0_13"
> Java(TM) SE Runtime Environment (build 1.6.0_13-b03)
> Java HotSpot(TM) Server VM (build 11.3-b02, mixed mode)
>            Reporter: Knut Anders Hatlen
>            Priority: Minor
>
> I noticed that a table scan test performed significantly worse
> (10-20%) in Derby 10.5.1.1 than in Derby 10.4.2.0. I only see this if
> the test creates and populates a fresh database. To reproduce, put
> derbyTesting.jar from 10.5.1.1 and derby.jar from the release you want
> to test in your classpath, and execute the following shell commands:
> # make sure the database is removed so that we create a fresh one
> test -d db && rm -rf db
> # run test for five minutes (+ one minute warm-up)
> java -server -Dderby.storage.pageCacheSize=25000 \
>     org.apache.derbyTesting.perf.clients.Runner \
>     -load sr_select -load_opts nonIndexed -wt 60 -rt 300 -init

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