Re: Minimal storage

Toby Dickenson wrote:

> On Thursday 24 June 2004 13:42, Dario Lopez-Kästen wrote:
> 
>>I am looking for a storage that is not rambased that will be usefull for
>>storing semi-transient data, like sessioning data and cache information.
> 
> 
> It rocks. I regularly use it in this manner when I use a ZODB as a cache for 
> big computations. setting sync=0 and turn off md5 checking in the config file 
> makes it faster than Filestorage for sizes above a few megabytes. 

That is great news indeed. I am looking for storage replacments for 
zope's sessioning mechanims that allows it to work with ZEO. I am also, 
at least temporarily, trying to avoid coding a new SQL-based sessioning 
mechanism, mostly due to time constraints.

Minimal seems perfect for this.

> [There is an experimental DirectoryStorage.Full packing implementation that 
> uses DirectoryStorage.Minimal. It creates a new storage, uses it during the 
> packing process to store the per-file mark/sweep bits, then "rm -rf" the 
> minimal storage directory at the end. That method would be the default today, 
> except for ZODB leaking memory when a database is closed.]

OK - I assume that this would speed up packing?

>>Is Minimal still being supported?
> 
> 
> It hasnt been actively maintained for a while, because the no-history design 
> is inconsistent with Full's main goal of robustness. DirectoryStorage.Minimal 
> doesnt have a consistency-checking tool, or replication. I would recommend 
> against using it for anything that needs long-term data durability, although 
> that clearly isnt a requirement for you.

Actually I think there is an "opportunity" here. IMHO, there is a lack 
of a good "use and throw away" temporary storage that is not RAM-based 
and works with ZEO.

There are things that, at least looking at my needs, I want to cache in 
a more persistent way than just using a RAM-based cache, and I also 
would like to have more control over the expiration time, etc - Not to 
mention the fact that I can have sessiosn that survive a Zope-client 
crash :-)

There are other intersting things that cen be done and that at least I 
have found a need for - implementing private namespaces, besides REQUEST 
is one of the. This is of course possible now, but would have generated 
a lot of growth in the ZODB requiring a lot of packing. ( I assume that 
no undo suppoort means that no packing is needed )

> As for support....  I dont have the 
> same commitment to supporting Minimal, because Im not using personally for 
> any important production systems. Having said that, Minimal.py is only about 
> 50 lines of code, so I dont anticipate any problems.

OK - I might be able to live with that - probably nothing will go very 
wrong :-). I can't say to what extent I might be able to fix anything 
wrong, should that happen, but if we get sufficiently dependent on this, 
i might eventually be able to ask my employer to provide some money, 
should the need for fixing arise...

> I hope that helps.
> 

Indeed it does. Thank you very much.

Sincerely,

/dario
-- 
-- -------------------------------------------------------------------
Dario Lopez-Kästen, IT Systems & Services Chalmers University of Tech.


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