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From "Emmanuel Lecharny (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAVIBOT-3) Update the Header only once when updating a BTree
Date Thu, 15 Aug 2013 14:59:48 GMT

    [ https://issues.apache.org/jira/browse/MAVIBOT-3?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13741031#comment-13741031
] 

Emmanuel Lecharny commented on MAVIBOT-3:
-----------------------------------------

FTR, I counted the number of updates when we add 10 000 elements in a BTree :

- The RecordManager header is updated 137 071 times
- The BTree header is updated 39 996 times

In the mean time, we have flushed 39 996 PageIOs.

We can do better !

I'm quite sure we can update the BTree Header only once per Add operation, the very same for
the RM header. 
                
> Update the Header only once when updating a BTree
> -------------------------------------------------
>
>                 Key: MAVIBOT-3
>                 URL: https://issues.apache.org/jira/browse/MAVIBOT-3
>             Project: Mavibot
>          Issue Type: Improvement
>    Affects Versions: 1.0.0-M1
>            Reporter: Emmanuel Lecharny
>            Assignee: Emmanuel Lecharny
>            Priority: Critical
>             Fix For: 1.0.0-M2
>
>
> We currently update the RM Header for every page we write on disk. This is extremely
costly. We could gather all the changes and update the RM header only once.

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