Re: eXtensible Transaction Manager API

On 7 November 2015 at 16:53, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
wrote:

> On 11/07/2015 05:11 PM, Amit Kapila wrote:
>
>
> Today, while studying your proposal and related material, I noticed
> that in both the approaches DTM and tsDTM, you are talking about
> committing a transaction and acquiring the snapshot consistently, but
> not touched upon the how the locks will be managed across nodes and
> how deadlock detection across nodes will work. This will also be one
> of the crucial points in selecting one of the approaches.
>
>
> Lock manager is one of the tasks we are currently working on.
> There are still a lot of open questions:
> 1. Should distributed lock manager (DLM) do something else except
> detection of distributed deadlock?
> 2. Should DLM be part of XTM API or it should be separate API?
> 3. Should DLM be implemented by separate process or should it be part of
> arbiter (dtmd).
> 4. How to globally identify resource owners (0transactions) in global lock
> graph. In case of DTM we have global (shared) XIDs,
> and in tsDTM - global transactions IDs, assigned by application (which is
> not so clear how to retrieve).
> In other cases we may need to have local->global transaction id mapping,
> so looks like DLM should be part of DTM...
>

Yes, we need a Distributed Lock Manager, but I think its a separate thing
from the DTM.

(I'm loath to use the phase DLM, which was used within Oracle Parallel
server for a buffer lock manager, which is not what is being discussed).

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