[jira] Updated: (DERBY-888) improve performance of page allocation

["Kathey Marsden (JIRA)" <de...@db.apache.org>]

     [ http://issues.apache.org/jira/browse/DERBY-888?page=all ]

Kathey Marsden updated DERBY-888:
---------------------------------

    Component: Store

> improve performance of page allocation
> --------------------------------------
>
>          Key: DERBY-888
>          URL: http://issues.apache.org/jira/browse/DERBY-888
>      Project: Derby
>         Type: Improvement

>   Components: Store
>     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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