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https://issues.apache.org/jira/browse/DERBY-646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12689121#action_12689121
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Kristian Waagan commented on DERBY-646:
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Thanks for testing the new feature, Knut Magne :)
I'm currently working on a patch, where I'm considering using java.io.File.
That should take care of any other OS that has a different style for paths as
well.
Feel free to log a bug in Jira. If you don't, I will tomorrow.
Regarding memory footprint, you have to balance the memory overhead against
performance. Setting the page cache to the minimum size will degrade
performance in many configurations.
The worst case I saw in my simple testing, was a drop from 28361
(pageCacheSize=1000) tps to 4059 (pageCacheSize=40) tps. This was a single
record update test using a page size of 32 K.
I'm not quite sure how you would go about discarding the log records, but you
do need the UNDO log records to support transactions. Doing something in this
area should be possible.
I don't know the log system well enough to say something more, but maybe
someone else does?
> In-memory backend storage support
> ---------------------------------
>
> Key: DERBY-646
> URL: https://issues.apache.org/jira/browse/DERBY-646
> Project: Derby
> Issue Type: New Feature
> Components: Store
> Affects Versions: 10.5.0.0
> Environment: All
> Reporter: Stephen Fitch
> Assignee: Kristian Waagan
> Attachments: derby-646-1a-raw-compiles.diff,
> derby-646-1a-raw-compiles.stat, derby-646-20090222.diff,
> derby-646-20090222.stat, derby-646-2a-vfmem_first_rev.diff,
> derby-646-2a-vfmem_first_rev.stat, derby-646-2b-vfmem_first_rev.diff,
> derby-646-3a-jmx_experiment.diff, derby-646-performance_comparison_1a.txt,
> svn.diff
>
>
> To allow creation and modification of databases in-memory without requiring
> disk access or space to store the database.
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