On 3/22/16 9:36 AM, Amit Kapila wrote:
> > > Note, that we are doing it only when a transaction has less than
> equal to
> > > 64 sub transactions.
> >
> > So?
> >
>
> They should fall on one page, unless they are heavily interleaved as
> pointed by you. I think either subtransactions are present or not, this
> patch won't help for bigger transactions.
FWIW, the use case that comes to mind here is the "upsert" example in
the docs. AFAIK that's going to create a subtransaction every time it's
called, regardless if whether it performs actual DML. I've used that in
places that would probably have moderately high concurrency, and I
suspect I'm not alone in that.
That said, it wouldn't surprise me if plpgsql overhead swamps an effect
this patch has, so perhaps it's a moot point.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
