Re: Derby and HA-JDBC

[Kurt Huwig <k....@iku-ag.de>]

Am Montag, 24. September 2007 schrieben Sie:
> Hi,
>
> I understand from your postings to the Derby user list that you are
> using HA-JDBC with Derby. We are considering whether HA-JDBC is
> something we can recommend to customers who are asking for HA support
> for Derby. Hence, it would be very interesting to us to hear about
> your experience with HA-JDBC:
>
>   - In what configuration do you use it?  How many Derby back-ends?
> How many clients?

Two JVMs, each contains an embedded Derby and offers network access. 
Each node is configured with a local embedded Derby and accesses the 
other node via the network client. Read acces is only local, to take 
advantage of the embedded database.

>   - Is your main purpose get higher availability, or to be able
>     partition the load across more servers (load-balancing)?

Higher availability.

>   - How easy/difficult is it to get started using HA-JDBC?

Very easy: just replace the JDBC driver and insert old driver/credential 
into the ha-jdbc.xml

>   - From your experience, what kind of applications is HA-JDBC well
>     suited for?  (e.g. is it best for read-mostly access?) What types
>     of application is not that well suited to use HA-JDBC?

I just used it for this one application and it worked fine. We are 
having some issues with race conditions across nodes, despite we are 
using distributed transactions due to a "insert or update"-logic. I 
patched HA-JDBC to simply ignore duplicate-key-exceptions which works 
fine.

>   - Have you had particular issues with HA-JDBC/Derby that you have
> had to work around?

I found some bugs, each of them has been fixed within hours. The 
developer is very friendly and even logged into a system of mine to 
debug some problems.

> I hope are willing to share some of your experience with us either by
> email directly to me or by posting to derby-user.

Sure. I only used version 1.1 of it. Version 2.0 has been released some 
time ago.
-- 
Mit freundlichen Grüßen

Kurt Huwig (Vorstand)
Telefon 0681/96751-50, Telefax 0681/96751-66
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