[aida] 6.2 news: Image based persistency

Friedrich Dominicus frido at q-software-solutions.de
Fri Feb 25 07:58:19 CET 2011


Chris Muller <asqueaker at gmail.com> writes:

> I am not against image-based persistency, I just was saying that I
> like to be conservative about _advocating_ it, particularly in this
> manner that ignores the 2nd RM prong..
I for my part have understood it that way. I just can see wha Janko has
used it in Aida. It really IS a solution for "hobbyists" and not so
large projects. And well as I  understood he does make snapshots every
once in a while. So the data which are  lost are thos which were changed
after the last snapshot. Or am I missing something?

>
>> With Eliot as VW VM designer now working on Squeak/Pharo VMs I'm sure we
>> will soon achieve similar stability and therefore suitability for
>> Squeak/Pharo image based persistency as well.
>
> I'm not sure what VM stability problems you refer to.  We've had
> non-Cog VM's running in production for years; zero downtime due to the
> VM.
I has experimented with Aida in January and Pharo simply has frozen. But
maybe it still was "alive"....
>
>>> What happens if the model grows faster than expected beyond memory
>>> capacity?  How do you get your app ported over to GemStone w/
>>> licensing, etc. and back up and running quickly?  How does one
>>> "upgrade their image" if the model is stuck in an old image?  Does the
>>> image save start to take longer and longer as the image grows?
>>
>> Those if not all reasons goes int that 1% of special cases I wrote. At
>> least on VW I upgrade an image by "filling-out" all objects and file in
>> on the fresh one. This is called BOSS-out/in on VW, while on
>> Squeak/Pharo I still need to check the right way doing it.
> Friedrich was also wrong when he referred to Magma as a relational
> mapper.  Rest assured, it is an ODBMS 100% with transparency
> comparable to GemStone.
You are right. I have meant GLORP. I'm sorry that I messed this up.
But then please let us learn more about Magma. I had a "hasty" look over
it and yes I had it installed once... 

>
> By "directly transferable" do you mean with zero code changes?  If so,
> that's really impressive!
I don't think that this is a bit asked too much. But it seems the effort
of the "ports" is not that demanding. But I may be wrong about it. I'm
just using it with Pharo

Regards
Friedrich


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