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https://issues.apache.org/jira/browse/DERBY-4940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12995441#comment-12995441
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Rick Hillegas commented on DERBY-4940:
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There is a discussion about reasonable defaults for the undocumented istat
knobs and about whether additional knobs are needed:
http://old.nabble.com/forum/Search.jtp?forum=105&local=y&query=question+about+istats+thresholds
This issue is a place to continue those discussions and, if necessary, to hang
patches. At the moment, we are still planning to not document these knobs.
Instead, we would like to gain experience about how istat behaves in the wild.
From that experience, we hope to figure out whether these are the right knobs,
how to set reasonable defaults for them, and whether we should document how to
override Derby's defaults.
> 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: 10.8.0.0
> Reporter: Kristian Waagan
>
> 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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