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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-4940) Tune istat operational characteristics
Date Thu, 17 Feb 2011 11:59:24 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Kristian Waagan updated DERBY-4940:

    Attachment: derby-4940-1a-absdiff_to_1k.diff

Attaching patch 1a, which changes the default setting of the absdiff threshold to 1000. This
will hopefully stop the tinderbox and the nightlies to fail due to failures in the various
updatelocks tests.
Whether the absdiff mechanism will be kept or not is up for discussion, this commit is primarily
to try to stabilize the regression tests.

Committed to trunk with revision 1071588.

> Tune istat operational characteristics
> --------------------------------------
>                 Key: DERBY-4940
>                 URL: https://issues.apache.org/jira/browse/DERBY-4940
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions:
>            Reporter: Kristian Waagan
>         Attachments: derby-4940-1a-absdiff_to_1k.diff
> The istat feature relies in a few tuning parameters to work properly.
> The main goals of the feature is to avoid stale statistics degrading query performance,
and at the same time not interfere too much with user activity. Some study of applications
"in the field" is necessary to properly size the set of parameters.
> It is also clear that it is impossible to make the feature behave exactly as wanted for
all types of applications. Users that want full control of their statistics, can disable the
istat daemon and manually monitor and update the statistics.

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