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From "Mike Matrigali (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5503) Measure the performance degradation incurred by encrypting Derby databases
Date Wed, 16 Nov 2011 19:00:53 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13151423#comment-13151423

Mike Matrigali commented on DERBY-5503:

I only skimmed the links you provided, but enough to see that it seems like there is a lot
a varibility based on OS and filesystem.   

>From your numbers I am thinking that on the read only test your setup loads the unix cache
with decrypted blocks and then the tests basically never have
to do any decrypt on the subsequent readonly test runs.  There may be system specific ways
to clear unix cache but only way I can think that 
is completely safe is to do setup/creation of a large table, shutdown machine, do one run
on the table.  That will guarantee read from disk and decryption happening.

I don't have any explanation for the update encrypted filesystem.  Would be interesting to
see if system is waiting more in this case or if it is really
spining the cpu doing encryption.

On a side note, scanning through the documentation it seemed like there were a lot of options
in the encrypted filesystems to turn sync write requests into async write requests without
the application knowing.  This is a recipe for corrupted derby databases on system crashes.
> Measure the performance degradation incurred by encrypting Derby databases
> --------------------------------------------------------------------------
>                 Key: DERBY-5503
>                 URL: https://issues.apache.org/jira/browse/DERBY-5503
>             Project: Derby
>          Issue Type: Task
>          Components: Store
>    Affects Versions:
>            Reporter: Rick Hillegas
> It would be good to measure the performance degradation incurred by Derby's encryption.

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