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From "Sunitha Kambhampati (JIRA)" <derby-...@db.apache.org>
Subject [jira] Resolved: (DERBY-218) Add Relaxed Durability option
Date Mon, 23 May 2005 03:11:57 GMT
     [ http://issues.apache.org/jira/browse/DERBY-218?page=all ]
     
Sunitha Kambhampati resolved DERBY-218:
---------------------------------------

    Resolution: Fixed

committed this change with svn 169538.
Changes include:
1)To enable this no syncs mode, the property setting  is derby.system.durability=test  If
it is set to any other value other than test, then this property setting is ignored and the
system will default to the usual mode where all syncs happen correctly.
2) If database is booted in this mode then the  flag  to indicate this mode is being used
is set in log.ctrl file and it will not change after that.Thus there wont be any switching
between this mode ( no syncs) to default ( all syncs) mode because we cannot guarantee that
the database will be in a consistent state once its booted in this no sync mode..
3) This  flag is now written out as part of the log control flags in log.ctrl file instead
of using a spare byte. 
4) Syncs not forced for
-  the log file at each commit
- the log file before data page is forced to disk
- page allocation when file is grown
- data writes during checkpoint


> Add Relaxed Durability option
> -----------------------------
>
>          Key: DERBY-218
>          URL: http://issues.apache.org/jira/browse/DERBY-218
>      Project: Derby
>         Type: Improvement
>   Components: Store
>     Versions: 10.1.0.0
>  Environment: all
>     Reporter: Sunitha Kambhampati
>     Assignee: Sunitha Kambhampati
>      Fix For: 10.1.0.0

>
> Dan Debrunner posted a fix to allow for relaxed durability changes in http://article.gmane.org/gmane.comp.apache.db.derby.user/681/match=relaxed+durability
> 1) Need to add this option in Derby maybe as some property
> 2) Also from discussions on the list, Mike suggested that 
> - that the logging system be changed to somehow
> record that the database has operated in this manner, so that if
> the database goes corrupt we don't waste effort trying to figure out
> what when wrong.  Probably need some way to mark the log records, the
> log control file and write a message to the user error log file.

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