Re: Transaction management in Ozone

Hi Filip,

söndagen den 30 maj 2004 23.04 skrev Filip Kinsky:
> Hi,
> I'm just writing my dissertation work on Opensource ODBMS (and
> Ozone;)) and just now, I'm collecting some information about
> transaction management in ODBMSs - how is this solved in Ozone? is
> there classical pessimistic locking used? And is Ozone full
> ACID-compliant?

Yes it is ACID compliant except for some extreme cases such as server power 
failure which under certain unfortunate circumstances can corrupt the 
database.

Yes, we have pessimistic locking with Multiple Reader One Writer (MROW) locks. 
objects are locked when they are accessed. The lock level (READ, UPDATE, 
WRITE) depends on the lock level that is specified by the proxy for the 
method that is called. Optimistic looking is on the todo list.

> And the second problem I'm just now focused on - is there any support
> for indexing (attributes) and searching? I don't think so, but I'm
> rather asking...

We do not support user managed indexing today. It would make sence to have 
this for the XML module and later if we have some sort of ad hoc query 
functionality... For the type of pure java based object access commonly used 
for an ozone application there is no need for user defined indexing IMHO.

>
> thanks in advance for any information and sorry for little OT...
> Filip Kinsky
>
> PS: I'd really appreciate some more information sources on ODBMSs'
> theory - transaction management, indexing etc... regardless of the
> database product...

Look in the developer guide and users guide. Let us know what you find missing 
(or better yet, write the pieces you find missing ;) ) and we'll include it 
in the docs somewhere.

Best regards,
Per


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