[Mulgara-general] Re: [Mulgara-dev] The future of Mulgara. What is 'XA2' and how will it benefit you.
Andrae Muys
andrae at netymon.com
Wed Nov 29 12:07:18 UTC 2006
On 29/11/2006, at 5:44 PM, Tate Jones wrote:
> An accurate understanding of the problem. From memory Kowari was
> heavily IO bound after 250 million.
>
> Some additional thoughts for the document
>
> - Isolation levels - should XA2 support phantom and repeatable
> reads? Configurable at the session transaction level?
The proposed isolation level is higher than 'no_phantom_reads', but
falls just short of 'serialisable'. I am almost convinced that
serialisable cannot be obtained without locking.
OTOH, applications requiring RDFS/OWL consistency semantics will
require serialisability, so there I am proposing that we should
eventually provide a lock-service, that will provide the level of
guarantees RDFS/OWL applications require (provided no application by
passes the lock by using RDF semantics directly).
I still have some work to do finishing the documentation for the
transaction rearchitecture. When that's done my top priority is
preparing a paper/seminar to cover these issues in greater depth.
> - Simple test plan (how to confirm the scalability, performance and
> robustness)
Robustness is hard to 'test'. I have previously proposed a move to
crash-only shutdown as a means to provide some of this. Ultimately
robustness will be a matter of specifying robust semantics, and
providing some sort of verification (probably manual inspection).
Scalability and performance are easier to measure. Insert speed is
naturally important for various varieties of dataset. Some benchmark
queries will also be required. What figures of merit are people
interested in?
> On 27/11/2006, at 11:27 AM, Andrae Muys wrote:
>>
>> http://www.netymon.com/papers/XA2-Discussion-Paper.pdf
--
Andrae Muys
andrae at netymon.com
Principal Mulgara Consultant
Netymon Pty Ltd
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