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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5684) Explore possible istat daemon improvements and optimizations
Date Mon, 14 May 2012 15:07:52 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5684?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13274664#comment-13274664
] 

Kristian Waagan commented on DERBY-5684:
----------------------------------------

Thanks for the comments, Dag.

I've stumbled across some challenges when it comes to testing, and I've also identified some
other problems with the patch you reviewed.
See my comments below.

DW> I think I'd reverse the logic here for clarity to: ...
I'll consider this in the next rev of the patch.

DW> Essentially a set: qualifiedCds, implement as such?
Yes, that'll probably make the code more readable. In store even lists are pretty much avoided,
so I think've been influenced by that pattern! However, the code in the IndexStatisticsAnalyzer
isn't performance critical, so it's better to favor readability. The code has changed by now,
but I'll see if the suggestion is still applicable.

DW> What scenario corresponds to this latter case below (irg == null):?
I don't remember... I'll remove irg == null and see if I added it because a test fell over
(I think so, but maybe I had a bug somewhere else that caused this behavior).

DW> What are the pros and cons here? I would assume both should invalidate?
Yes, both should invalidate, the question is when. The daemon can commit stuff as it goes,
not sure how this works with alter table. I'll check this more.

I'm rerunning tests with a newer version of the patch. I'm getting a bit worried the changes
are getting too big to push this close to the release, but we can take that discussion when
the patch is ready :) I believe there are things we can to to reduce the risks.
                
> 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-1.diff, derby-istat-exploration-2.diff,
derby-istat-exploration.diff
>
>
> A task tracking some experiments on the istat daemon and the statistics update code.

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