[ http://issues.apache.org/jira/browse/DERBY-888?page=all ]
Mike Matrigali resolved DERBY-888:
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Fix Version: 10.2.0.0
Resolution: Fixed
> improve performance of page allocation
> --------------------------------------
>
> Key: DERBY-888
> URL: http://issues.apache.org/jira/browse/DERBY-888
> Project: Derby
> Type: Improvement
> Reporter: Mike Matrigali
> Assignee: Mike Matrigali
> Priority: Minor
> Fix For: 10.2.0.0
>
> Improve performance of page allocation by no longer requiring sync of the
> allocated pages. The reason for the sync
> currently is so that during redo recovery we did not have to handle the case
> of redoing the allocate and finding no space
> available on the disk. During tasks like single user load this sync
> allocation is a significant performance issue - in the
> case where one does 1000 insert per transaction the total time aproaches very
> close to durability=test where no syncing
> is done in the whole system.
> For instance in a test of loading a 150 meg db with a number of tables and
> indexes, on a 1.7 ghz laptop with one ide disk,
> sun jdk1.4.2, windows XP
> i got the following types of results:
> default system: 6 minutes
> no alloc sync: 1 minute, 43 seconds
> no syncing: 1 minute , 1 second
> Once syncing is disabled then recovery must be enhanced to handle the
> possible out of space condition. Recovery already
> handles out of space during undo, so this will just handle the error the same
> as that. It will stop recovery and produce an error
> indicating that user must add disk space and rerun recovery before system can
> be brought online. I actually think on most
> JVM's/OS's this won't happen as the system will still be asking the JVM/OS
> for the space, just not syncing the values in those
> pages to disk. Most OS's at this point will reserve the space in the file
> tables and not let others grab that space.
> This project will make sure that out of space recovery path has tests. It
> will also make sure that redo recovery encountering garbage
> in a newly allocated page during redo of an create page is tested.
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