Re: eXtensible Transaction Manager API

On 2 November 2015 at 13:24, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
wrote:

> PostgreSQL assumes that top-level xid commit is atomic, along with all of
> its subtransactions. So the API having access to only Get/Set at the xid
> level would not work. We would need TransactionIdSetTreeStatus() rather
> than just SetStatus. GetStatus is not atomic.
>
>
> XTM API has function SetTransactionStatus but it actually encapsulate
> TransactionIdSetTreeStatus.
>

OK, thanks.

> At present, I can't tell whether you need subtrans and multixact calls in
> the API as well. I would imagine we probably do, though we might imagine an
> implementation that didn't support those concepts.
>
>
> Postgres-XL doesn't support subtransactions. Neither did we at this moment.
> Support of subtransactions will be our next step.
>

OK. I guess it depends where we want to put the patch; discussion here
means in-core, so for it to go in here, we do need subxacts etc.

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services