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Date: Sun, 6 May 2007 14:16:15 -0700 (PDT)
From: "Mike Matrigali (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Updated: (DERBY-1887) improve performance of single user
 long transactions.
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     [ https://issues.apache.org/jira/browse/DERBY-1887?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Matrigali updated DERBY-1887:
----------------------------------

    Component/s: Store

> improve performance of single user long transactions.
> -----------------------------------------------------
>
>                 Key: DERBY-1887
>                 URL: https://issues.apache.org/jira/browse/DERBY-1887
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions: 10.1.3.1
>            Reporter: Mike Matrigali
>
> The default logging option for Derby is to write a log page using the user thread, and wait for it to hit disk before allowing the user thread to continue.  For transactions that span multiple log pages these syncs are not necessary (only need to sync when the user commits).  A common case for this is a single user in the system inserting blob/clob columns which in derby need to log the entire contents of the blob/clob.  
> Current Java provides a few options:
> 1) we could dynamically switch to the async writes with a sync at the end.  This would require closing and opening the log file to change the syncing mode.
> 2) we could push the log writer io to a different thread than the user thread.
> there may be others.
> Note that this is mostly a single user problem, as when multiple users are involved other threads can continue operating while whatever user thread has been chosen waits for the sync.  This includes adding more log data to the inmemory log buffer.

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