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From "Kristian Waagan (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5684) Explore possible istat daemon improvements and optimizations
Date Wed, 04 Apr 2012 20:45:27 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5684?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Kristian Waagan updated DERBY-5684:

    Attachment: derby-istat-exploration.diff

Attaching a first patch showing some experiments I did on the istat code (based on existing
JIRAs and the current discussions on derby-dev).

This is highly experimental code.
There are some failures in the tests.

Feel free to comment on the general approach, take the patch for a spin,  and/or suggest further
improvements :)

What it does:
 o deletes orphaned stats
 o don't generate statistics for single-col unique indexes
 o use index row estimate (instead of scanning) for single-row non-unique indexes backed by
a unique index (i.e. foreign key)

(ps: I'll be offline for some vacation, so don't expect any quick answers from me)
> Explore possible istat daemon improvements and optimizations
> ------------------------------------------------------------
>                 Key: DERBY-5684
>                 URL: https://issues.apache.org/jira/browse/DERBY-5684
>             Project: Derby
>          Issue Type: Task
>            Reporter: Kristian Waagan
>         Attachments: derby-istat-exploration.diff
> A task tracking some experiments on the istat daemon and the statistics update code.

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