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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-646) In-memory backend storage support
Date Wed, 25 Feb 2009 21:09:02 GMT

    [ https://issues.apache.org/jira/browse/DERBY-646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12676783#action_12676783
] 

Rick Hillegas commented on DERBY-646:
-------------------------------------

For the first time in the history of the Derby community, two complete implementations of
a significant feature have surfaced almost simultaneously. I'm afraid we have to pick one.
I hope that the other contributor does not feel snubbed. Thanks to Kristian and Cheng for
these two great submissions.

I have taken a quick look at the patches and at the commentary on this JIRA. I prefer Kristian's
implementation for the following reasons:

1) The coding style is slightly easier for me to understand.

2) According to the performance data which Kristian posted, his implementation is slightly
faster.

I hope that Cheng's ICLA arrives soon so that we can mine his patch for ideas that can be
layered on top of Kristian's work. For instance,

A) Cheng's solution lets you snapshot the database to disk at shutdown time. I think some
users will find this useful. I understand that we could simulate this behavior using backup
and restore, but I would not discount the appeal of this automatic behavior. Perhaps the api
here could be an additional subprotocol.

B) Cheng's solution has a finalizer method. This seems particularly useful for delivering
(A) in the face of a system crash. But winddown logic seems generally useful for a complicated
program like an rdbms.

C) Cheng provides some additional tests. Some of these tests may be implementation-agnostic
and worth running against Kristian's implementation. It would be helpful if Cheng could describe
these tests in greater detail so that we can decide whether to incorporate them.

Thanks again to both Kristian and Cheng.

> 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
>         Environment: All
>            Reporter: Stephen Fitch
>         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-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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