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From <de...@segel.com>
Subject RE: Many background threads (rawStoreDaemon)
Date Mon, 04 May 2009 12:12:40 GMT


> -----Original Message-----
> >> I have an application that opens several small derby databases (using
> >> EmbeddedDriver).
> >> Most of of these instances don't handle many requests.
> >> The problem is that each instance maintain its own thread
> >> "derby.rawStoreDaemon".
> >> Is there a way to use a thread pool shared between instances instead ?
> >> (There is also a discussion about that here:
> >> http://osdir.com/ml/apache.db.derby.devel/2005-04/msg00093.html)
> >
> > I am not aware any progress has been made on this issue, unfortunately.
> 
> If you think it should be adressed, filing a JIRA issue is a good first
> step: https://issues.apache.org/jira/browse/DERBY
> 
> (I don't think there is one filed yet, is it?)

Ok so if I understand this...

A person wants to open multiple embedded copies of a database and then
thread pool the database server connections/controllers of the individual
database connections.

Ok, yes there is some merit to this. Unfortunately, you're adding a lot of
weight to the code that means a larger footprint making it harder to embed.

This is why I've periodically have had to ask... what is the direction you
want Derby to take? 

Do you want a small footprint lightweight database, or do you want more
features that you will find in a more commercial database?

If you say 'both' then you've got to do a lot of refactoring to allow for
some sort of 'plug n play' class loader or even jar builder which allows you
to pick and choose which features you want to run within your engine.

An example... being able to set a property value that indicates which (if
any) encryption algorithm you want to use within derby. (md5,WPA,AES,
twofish...) Then when you build derby for deployment, you only include the
packages you need.  Or if you had a feature like table partitioning, you
could decide to include it, or not.

But that would be a radical change and a lot of work to be done for a 'free'
community project.  Unless you're a Phd candidate with time on their
hands... do you really want to dive in to this?

Sorry for the soap box. Its Monday and the capitalism in me is waking up.
;-)

-Mike



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