Its an embedded java based database.

http://www.h2database.com/html/frame.html

David, I would be interested in hearing your thoughts on the current
JDBC datastore api. The general concencus from myself and the other jdbc
module maintainers is that it requires some cleanup / re-archtecting,
etc... Do you concur?

This wouldn't really be something we would force on the current jdbc
modules. They work well as written, even if a bit hard to maintain. What
we would really like is to have a good example of what a maintainable
jdbc datastore would look like. And come up with a high level of test
coverage for it.

With these in hand, jdbc module maintainers like you and myself would be
in a better position to possibly switch over.

-Justin

David Adler wrote:
> What is H2?
> 
> I'm certainly interested in the JDBC and DataStore topic, although
> fixing this may be considerable work.
> 
> David
> 
> Chris Holmes wrote:
>> Yeah, that sounds ideal.  The abstract JDBC infrastructure is
>> obviously hosed right now - the reality of working with it ends up
>> making things more difficult due to the amount of hacks to get the
>> subclasses working.
>>
>> I agree that H2 would be a great time to have another go at JDBC
>> helper methods or abstract methods that are actually useful and don't
>> impose a burden.  I imagine that a couple abstract helper methods
>> might still be useful, but that much of what we try to do is likely
>> better off in some utility classes.  We've had a lot of good lessons,
>> and we should try to learn from them, make it easier for others to
>> write new jdbc datastores.  Should definitely talk to David Adler as
>> well, he had some ideas on how to make it easier as well.  If we build
>> a nice infrastructure it should be relatively easy for existing
>> datastores to port over if they choose.
>>
>> Chris
>>
>>
>>
>> Justin Deoliveira wrote:
>>> Hi Andrea,
>>>
>>> Thanks for your thoughts. About PostGIS, originally rewriting it seemed
>>> like a good idea. But for the exact same reasons you listed. Reproducing
>>> the functionality while making the code cleaner is no simple task. Part
>>> of making the code cleaner is getting rid of some of those hacks, which
>>> then changes the datastore. For these reasons, I dont think its
>>> realistic to take on this kind of effort.
>>>
>>> However, what I would really like to see is a good abstract JDBC
>>> datastore. One made with the intent to extended. Breaking out "template"
>>> methods where needed, making it final if need be, etc...
>>>
>>> It seems like there is a fair amount of interest in having an H2
>>> datastore. I was thinking this might be a much more logical candidate to
>>> do this type of thing with, since there are no pre-existing expectations
>>> to live up to.
>>>
>>> -Justin
>>>
>>> Andrea Aime wrote:
>>>> Hi,
>>>> two things Jody said during yesterday IRC meeting made
>>>> me think tonight.
>>>>
>>>> I don't have the logs for the pre-meeting, but the first
>>>> one was something like how deep is the level of optimizations,
>>>> workarounds and details in the postgis data store, and how
>>>> nice is the new experimental one.
>>>>
>>>> The old one is ugly, no doubt. Making a new one with a cleaner
>>>> structure is a good move for long term mantainance. I agree
>>>> on this too.
>>>> Yet, the "level of optimizations, workarounds and details"
>>>> is what makes the postgis data store our best jdbc data store,
>>>> that is, something that most of the time just works fine,
>>>> with whatever load of data you throw at it, and with various
>>>> levels of badness handled transparently.
>>>>
>>>> What I would like to make people appreciate is the amount
>>>> of work that went into the old ugly data store, days of fine
>>>> tuning, bug fixing that are not evident and not checked by
>>>> just the unit test suite. Making a new one that passes the
>>>> same tests as the old one is just a first step towards something
>>>> that can be used as a replacement.
>>>> Before venturing into such a change, one has to understand
>>>> intimately the old and ugly one, appreciate the why and the hows
>>>> things were done in a certain way.
>>>>
>>>> As an alternative, that may work on widely used modules, check
>>>> out the list of closed bugs on the module and ask yourself whether
>>>> there is a test for them, and whether the new module exhibit
>>>> the bad behaviour described in there.
>>>> If we all added a junit test for each bug found, that would not
>>>> be necessary, but since history proves otherwise, it's an
>>>> exercise everyone doing big changes should try out.
>>>>
>>>> This is not to say that we don't need change. We do.
>>>> But we need a change that provides improvements, not regressions.
>>>> A big changes that disregards detailed correctness and performance
>>>> issues is a sample of the "small blanket" problem,
>>>> you try to cover your shoulders, and end up with cold feet.
>>>>
>>>> So every time you work on a big change, think about it also
>>>> from this point of view :-)
>>>>
>>>> Cheers
>>>> Andrea
>>>>
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>>>>
>>>
>>>
>>
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-- 
Justin Deoliveira
[EMAIL PROTECTED]
The Open Planning Project
http://topp.openplans.org

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