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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-4233) Lower tablescan performance right after database creation in 10.5
Date Fri, 22 May 2009 13:58:46 GMT

     [ 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:
>         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 than in Derby I only see this if
> the test creates and populates a fresh database. To reproduce, put
> derbyTesting.jar from 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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