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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5770) Reduce window of opportunity for queries being compiled without statistics on istat update
Date Fri, 18 May 2012 06:00:13 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5770?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kristian Waagan updated DERBY-5770:
-----------------------------------

    Attachment: derby-5770-1a-move_invalidation.diff

Attaching patch 1a, which moves the invalidation and removes the use of a boolean variable
in invalidateStatements.
                
> Reduce window of opportunity for queries being compiled without statistics on istat update
> ------------------------------------------------------------------------------------------
>
>                 Key: DERBY-5770
>                 URL: https://issues.apache.org/jira/browse/DERBY-5770
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.9.0.0
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>            Priority: Minor
>         Attachments: derby-5770-1a-move_invalidation.diff
>
>
> Currently the invalidation of statements accessing a table is issued before dropping
the old statistics and writing new ones. While we cannot guarantee that all compilations will
see the new statistics (we can currently only drop all statistics for an index, so we cannot
add the new ones first and then drop the old ones), we can do the invalidation after the work
has been done to reduce the chances that queries are compiled without statistics at all.

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