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From Rodney Waldhoff <rwaldh...@apache.org>
Subject RE: Derby embedded in Geronimo
Date Thu, 14 Oct 2004 22:02:09 GMT
On Fri, 1 Oct 2004, Noel J. Bergman wrote:

> Jeremy Boynes wrote:
>
>> If things work out well and there are no objections I plan
>> to switch away from Axion as our default embedded database.
>
> Obvious question would be why.  Seems as if there are some technical
> reasons.  As I understand them, totally hearsay, they are:
>
>  Axion: faster startup time,
>         great for unit testing
>         each transaction has its own copy of data
>         Oracle compatible SQL dialect (sequences, etc.)
>         ~400K
>
>  Derby: XA support
>         multiple concurrent users
>         transactions use locking
>         DB2 compatible SQL dialect
>         ~3MB
>
> Is that correct?  Anything else?  Both are good, but with some differences,
> so it might be helpful to have a comparison matrix if there are knowledgable
> people who would contribute to it.
>

I know this is an old thread, but just to clear up any misconceptions:

(1) Axion supports multiple concurrent users

(2) Axion supports "snapshot isolation" transactions, which sorta acts 
like "each tranaction has its own copy of data", but that's not really 
what's going on.  Oracle and PostgreSQL also support snapshot isolation, 
among others.

> 	--- Noel

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