Re: [RFC, POC] Don't require a NBuffer sized PrivateRefCount array of local buffer pins - Mailing list pgsql-hackers

On 2014-04-09 10:26:25 -0400, Tom Lane wrote:
> Andres Freund <andres@2ndquadrant.com> writes:
> > It's not unreasonable to argue that we just shouldn't optimize for
> > several pins held by the same backend for the same and always touch the
> > global count.
> 
> NAK.

Note I didn't implement it because I wasn't too convinced either ;)

> That would be a killer because of increased contention for buffer
> headers.  The code is full of places where a buffer's PrivateRefCount
> jumps up and down a bit, for example when transferring a tuple into a
> TupleTableSlot.

On the other hand in those scenarios the backend is pretty likely to
already have the cacheline locally in exclusive mode...

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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